# 6B 12/5-Maths (Angles in triangles)

Yesterday you all learnt that the THREE angles in a TRIangle total 180 degrees (a + b + c = 180).
Today we will be moving on to looking at angles in triangles in “Special Cases”. The video below explains the learning and shares examples for you to work on.

Miss Ahmed’s maths group

Miss Ahmed’s maths group reasoning challenges

Miss Vega and Mrs Hurt’s maths group

Miss Vega and Mrs Hurt’s Reasoning challenge

## 27 thoughts on “6B 12/5-Maths (Angles in triangles)”

1. Jessica M.

Isosceles triangle.
I know this because a isosceles triangle has two sides.
The degrees for M is 75.
There are two if the same degrees because the two lengths are the same.
An isosceles triangle has two equal sides.
1)68 degrees.
2)44 degrees.
3)59 degrees.
4)62 degrees.
5)36 degrees.
6)90 degrees.
I disagree with Dexter because as you can work out the answer of the other two angles.all you have to do is takeaway 28 from 180 then you have to divide it by 2 and that will give you the answer to the question.
Alex as an isosceles triangle because only two of the sides of the triangle are the same.
No has an isosceles triangle because only two of the sides are the same.
Eva has a equilaterl triangle because all of he sides are equal.

• Mrs Jones

Well done Jessica great work keep this up.

2. Abdulwahab E.

5a) 180-44=136
M=68° 44+68+68=180°

5b)180-61=119
n=59.5° 61+59.5+59.5=180°

5c)180-90=90
r=45° 90+45+45=180°

5d)180-60=120
8=60° 60+60+60=180°

6)I agree with the boy as the triangle is equilateral therefore you just have to divide 180 by 3 because all the sides are the same.

7)
a)false
b)false
c)true
d)true

8)The triangle is not an isosceles triangle because in an isosceles triangle there are 2 equal sides however in this triangle one angle is 43° another 74° and the missing one is 63 because 43+74=117 180-117=63°.

9)if one angle is 29° the other 2 could be 75.5 or two angles could 29° and the other angle is 122°

10)Angle c is 72 as this is a isosceles therefore 2 angles\sides are equal because of this b and c are equal.In addition, b is double the size of a therefore a=36 and 72+72+36=180°.

Reasoning
40+a+b=180°
40+a+d=180°
40+b+d+a+c=360°

• Mrs Jones

Well done Abdulwahab good work. How are you finding the work on angles? Have another look at Question 5 b) and 7 b,c.

3. Rahma M.

1) Isosceles triangle.
Isosceles triangle has two equal sides.
1a)m73
2)
isosceles triangles have two sides that are the same.
3.
3a)68 degrees=44 degrees
3b)59 degrees=62
3c)36 degrees
Triangle:90
4.
Dexter is incorrect if there is answer of the 2 angles there is 2 lengths of the triangle that are the same.If he take away 28 degrees from 180 degrees then divide that answer by 2 he would have got the correct answer.
5.
Then that would give him the answers for the other 2 angles which is
180-28=152 152 divided by 2 equals
Which would have gave him the answer;
77

• Mrs Jones

Hi Rahma, so pleased you are trying hard with your maths. Have another go at Question 1 a) and question 5.

• Rahma M.

-1a)m73
-Then that would give him the answers for the other 2 angles which is
180-28=152 divided by 2 equals
Which would have gave him the answer;
76

• Mrs Ahmed

Well done Rahma :)

• Rahma M.

Thank you

4. Amelia H.

5.
a). m=68
180-44=136
136/2=68
b). n=58
61+61=122
180-122=58
6.
Triangle has all equal sides and angles of 60.
7.
a). false – isosceles triangle has at least 2 equal sides.
b). true – equilateral triangles has always 3 sides equal.
c). false – right angle triangle wont have 3 equal sides.
d). true – right angle triangles can have 2 equal sides.
8.
The triangle is not isosceles because it has 3 different angles.
43+74=117
180-117=63
9.
1). 29+29=58
180-58=122
2). 180-29=151
151/2=75.5
10.
180= a+b+c
b=c -isosceles triangle has two angles equal.
b=2a so c=2a
expression can be written as:
180=a+2a+2a
180=5a
a=180/5=36
b=2×36=72
c=2×36=72
Reasoning:
20+a+b=180
20+c+d=180
20+70+90=180
20+90+70=180

• Mrs Ahmed

Thanks Amelia, not completely right. I think you need to catch up with the previous angle blogs from yesterday and last week.

How is your work pack coming along?

• Mrs Jones

Hi Amelia, it’s good to see you on the blog learning. You have done really well with these questions but as Mrs Ahmed has said it will benefit you to complete the previous days learning on angles.

5. Omar A.

5a) m=68
b)n=58
c)r=45
d)s=60

6) I agree with the boy because if there are lines on the sides shows that they are equal .

7a) False
b) False
c) False
d) True

8) The isosceles triangle is a triangle which has two equal sides which means it has two equal angles. The total of any angles in triangle is 180 degrees. So 43+74=117 and to figure out if the angles are equal we must take away 180 from 117 which gets us to our answer 63 this means we have three angles 43 , 74 and 63 therefore this means that this triangle is not an isosceles as it does not have two equal angles.

9) Possibility 1 We have two angle (29 and 29 ) and the remaining is 122.

Possibility 2 180 -29 = 151/2 = 75.5 for each angle.

10) Angle b is twice the size of angle a which means angle c is twice the size of angle a as b and c are equal.
Angle B and C are 72 =144 180-144= 36 72 is double of 36. So angle a is 36 and angle c is 72

Reasoning

20+90+70=180
20+90+70=180

20+a+b=180
20+c+d=180

• Mrs Jones

Hi Omar, really good work just take another look out question 7b please. How are you finding the work on angles?
It would be really nice if you good video yourself reading a chapter of our new class novel. Please let us know if you would like to do this.

Miss Vega and Mrs Hurt’s maths group
5)Work out the size of the missing angles
a) 180°-44°=136°
136°÷2= 68°
68°+68°+44°=180°
m=68°

b)61°+61°=122°
180°-122°=58°
61°+61°+58°=180°
n=58°

c)180°-90°=90°
90°÷2=45°
90°+45°+45°=180°
r=45°

d)60°+60°=120°
180°-120°=60°
60°+60°+60°=180°
s=60°

6) I disagree with Whitney because the triangle is an equilateral triangle which means all the angles are equal. Therefore to work out the angles you would do 180°÷3 which would give an answer of 60° which is what the size of the angles are.

7)Are the statements true or false?
a)Every isosceles triangle is equilateral. False
b)Every equilateral triangle is isosceles. True
c) A right angle triangle can be equilateral. False
d) A right-angled triangle can be isosceles. True

8) This triangle is not an isosceles triangle because two of the angles are not equal.
I worked out the missing angle(43°+74°=117° 180°-117°=63°) which is 63° and none of the angles are the same so it is not an isosceles triangle.

9)The other angles could be 29° and 122°.

10)Angle c is equal to 45 degrees because the bottom two angles are equal and 45°×2=90 which means 45°+45°+90°=180 so therefore angle c is equal to 45°.

Reasoning Challenge
b+a+20°=90°
40°+a+b=180°
a+b+20°=c+d+20°
a=d

• Mrs Ahmed

Super star, how are you finding this new angle learning?

I am finding this new angle learning fairly easy.

• Mrs Jones

Well done Hadisa you got them all right. Would you like to read a chapter of the class book and send it in to put on the blog?

7. Ayaan H.

1.Isosceles triangle.
I know its an Isosceles triangle becuse it has 2 equal sides and 2 equal angle
b. m=75
c. I notice that the Isosceles triangle has 2 equal side
A. a=68 b=44
b.c=59 d=59
c.e=36
d.f=90

• Mrs Ahmed

Good effort Ayaan, tell me three facts about angles in triangles.

• Mrs Jones

Good work Ayaan. Take another look at question 3 c) what is the value of d?

8. Anora N.

silver:
5a) m=68
5b) n=58
5c) r=45
5d) s=60

6) Whitney is incorrect because she should know that two of the angles are the same once she has worked out the two angles she can add them up and subtract it from 180 which will give her her third angle and then she needs to add all the three angles which should add up to 180.

• Mrs Ahmed

Well done Anora, how are you finding this angles unit so far?

• Mrs Jones

Great work Anora. Where are your answers for questions 7,8,9 and 10?

9. Sofia S.

1) Isosceles triangle.
1a) I know this because and Isosceles triangle has two equal sides.
1b)The amount of degrees for M is 75 degrees and then if I add 75+75 that will give me 150 and 150+30=180 degrees which is the total amount of degrees of a triangle.
1c) I noticed that there are two of the same amount of degrees because the 2 lengths are exactly the same.
1d) In an isosceles triangle has two sides that are the same.
Triangle A: a=68 degrees b=44 degrees
Triangle B: c= 59 degrees d=62
Triangle C: e=36 degrees
Triangle D: f=90 degrees
I disagree with Dexter as you can work out the answer of the other 2 angles because there is 2 lengths of the triangle which are the same if you take away 28 degrees from 180 degrees. Then divide that answer by 2.
Then this will give you the answers for the other 2 angles which is
180-28=152 152 divided bye 2 equals 76.
Alex has an Isosceles triangle because only 2 side of her triangle are the same.
Mo has an isosceles triangle because only 2 sides are the same.
Eva has an equilateral triangle because all of the sides are the equal

• Mrs Ahmed

Wowza, well done Sofia! Mo has a right angle so he has an ‘Isosceles right angle triangle’

How are you finding this new learning?

• Mrs Jones

Really great work Sofia, keep this up.