Question

∠A∠A and ​ ∠B∠B ​ are vertical angles with m∠A=xm∠A=x and m∠B=5x−80m∠B=5x−80 . What is m∠Am∠A ?

Answer 1

Vertical angles are the pairs of opposite angles made by two intersecting lines. One interesting feature of these angles is that they have equal measurements. Therefore we can solve m∠A as follows:

m∠A = m∠B
x = 5x - 80
6x = 80
x = 40/3

m∠A = 40/3

Answer 2

The Vertical Angles Theorem states that if two angles are vertical angles, then they are congruent .Given <A and <B are vertical angles so they are equal.

<A=<B.

Measure of <A=x and <B=5x-80

Or 5x-80=x

Adding 80 both sides

5x-80+80=x+80

5x=x+80

Subtracting x both sides

5x-x=x-x+80

4x=80

Dividing both sides by 4

x=20

Measure of <A= x= 20 degrees.