Question

what is the value of a? a - 42° a - 45° a a = °

Explanation:

Step1: Apply exterior - angle property

The exterior - angle of a triangle is equal to the sum of the two non - adjacent interior angles. So, $a=(a - 45^{\circ})+(a - 42^{\circ})$.

Step2: Expand the right - hand side

$a=a - 45^{\circ}+a - 42^{\circ}$.

Step3: Combine like terms

$a = 2a-87^{\circ}$.

Step4: Solve for $a$

Subtract $a$ from both sides: $0=2a - a-87^{\circ}$, then $a = 87^{\circ}$.

Answer:

$87$