Question

The value of a is :] Please help...

Answer 1

Step-by-step explanation:

Angle AOB = 5a (Vertically Opposite angles)

So 5a + 40° + 90° = 180° (Linear Pair)

=> 5a + 130° = 180°

=> 5a = 180° - 130°

=> a = 50°/ 5

=> a = 10°

Therefore a = 10°

Answer 2

Answer:

a = 10°

Step-by-step explanation:

Let the centre be O

given that,

∠AOF = 90°

∠BOC=40°

∠DOF=5a

Here from the figure we can say that,

∠DOF & ∠AOB are vertically opposite angles to each other

as we know that,

vertically opposite angles are equal

⇒∠DOF=∠AOB=5a

here by observing the given figure it is clear that CF is a straight line

as angle made by a straight line = 180°

we get,

∠AOF+∠AOB+∠BOC=180°

⇒90° + 5a + 40° = 180°

⇒130° + 5a = 180°

⇒5a = 180° - 130°

⇒5a = 50°

⇒a = 50°/5

⇒a = 10°

∴a = 10°

HOPE THIS WOULD BE HELPFUL FOR YOU