Question

Angle A is shown below.What is the measure of LA, in degrees?​

Answer 1

The measure of angle A is 55°.

Solution:

Let us take B be the adjacent angle of 145°.

Sum of the adjacent angles in a straight line = 180°

⇒ m∠B + 145° = 180°

Subtract 145° from both sides.

⇒ m∠B + 145° - 145° = 180° - 145°

⇒ m∠B = 35°

The adjacent angle of 145° is 35°.

In the image, angle B and angle A equal to 90°.

⇒ m∠B + m∠A = 90°

⇒ 35° + m∠A = 90°

Subtract 35° from both sides.

⇒ m∠A = 55°

The measure of angle A is 55°.