6W 13/05-Maths (Missing angles in triangles)

Today’s learning really counts on you having secure knowledge of angles on a straight line, vertically opposite angles, types of angles and how to calculate missing angles of triangles.

Everyone needs to complete this matching task when watching the videos. You can do this in your notebooks.

Miss Ahmed’s maths group
You must write your working out, you will need to add, subtract and complete inverse calculations.
E.g. If …. is a vertically opposite angle then … will be…
I know x + y = … then I have to subtract that total from 180 degrees to give me the missing angle. 180 – (x + y) = (missing angle)

Miss Vega and Mrs Hurt’s maths group

Select one of the reasoning questions to solve and explain.

14 thoughts on “6W 13/05-Maths (Missing angles in triangles)

  1. Silver :
    P = 48*
    Q = 124*
    R = 120*
    T = 128*
    S = 98*
    U = 104*
    V = 23*
    W = 36*
    Part 2 :
    C = 81.3*
    D = 15.7*
    X = 11*
    Possibilities are : 122 or 61

    Challenge : The first angle would be 36 and the second angle would be 72 because the third angle is 72, and on a isosceles triangle, the two sides are the same, and so 72 x 2 = 144, and then 180-144= 36 which is the first angle.

      • I found out that the first angle is 36 and the second angle is 72. The third angle is 72 so I did 180-72 which showed me the answer 108. Because the ratio from the first angle to the second angle is 1:2. That means the first angle is smaller. So the first angle is 36 degrees. The second angle is 72 degrees because on a isosceles triangle the sides are the same. So the third angle is 72 degrees that means the second angle is 72 degrees.

  2. Silver:
    1)
    a) p = 48o
    b )q = 124o
    c) r = 120o
    d) s = 98o
    e) t = 128o
    f) u = 104o
    g)v = 23o
    h) w = 36o

    2)
    a) c = 81.3o
    b) d= 15.7o

    3)x = 11o

    4)1st possibility = 122o
    2nd possibility = 140o

    • I am assuming these are meant to be degree signs?
      Good job. Can you solve this?

      Challenge – In a triangle, the ratio between the first and second angle is 1 : 2 and the third angle is 72. Find the first and second angle of the triangle.

  3. Silver:

    3)

    a) p = 47*. b) q = 124*

    c) r = 120* d) s = 32*

    e) t = 123*. f) u = 284*

    g) u = 59*. h) w = 77.5*

    4)

    a) c = 126.2*. b) d = 35.5*

    5)

    x = 29

    6)

    y only has one possible answer which is 122*

  4. 1.Work out the sizes of the angles marked with letters:
    a)p=48*
    b)q=124*
    c)r=120*
    d)s=98*
    e)t=128*
    f)u=104*
    g)v=23*
    h)w=36*
    2.Work out the sizes of the unknown angles:
    a)c=81.3*
    b)d=15.7*
    3.Work out the size of angle x:
    x=11*
    4.Find two possibilities of angle y:
    1st possibility=122*
    2nd possibility=140*

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