Question

The diagram shows three straight lines. Work out the sizes of a,b and c

Answer 1

Answer:

a=21°

b+110=180

b=70°

a+b+c=180

c=180-70-21

c=89°

Answer 2

GIVEN :  Exterior angle = 110° ; vertically opposite of angle a = 21°

TO FIND :  angle a, b, c

SOLUTION :

Sum of all the interior angles of triangle = 180°.

So, angle a+ b + c = 180°

Angle b + 110° = 180 °

So, angle b = 180° - 110°

angle b = 70°

angle a = 21 °

Because they are vertically opposite angle.

A+ B + C =180°

21° + 70° + C = 180°

91 ° + C = 180 °

C = 180° - 91°

C = 89°

As the sum of interior angles of triangle is 180°.

Angle a is 21°, b is 70° and c is 89° .