Answer:
Step-by-step explanation:
Comment
The key to this is to know what a remote angle is. A remote angle is one that has one leg in common with the exterior angle. Make this a little simpler.
The exterior angle is outside the triangle. In this case it is the 157 degree angle.
The two remote angles each contribute just one side to the exterior angle. <B contributes BC and <A
Theorem
The two remote angles = the exterior angle.
Equation
x + x - 21 = 157
Solution
x + x - 21 = 157 Combine the left side
2x - 21 = 157 Add 21 to both sides
2x - 21 + 21 = 157+21 Combine
2x = 178 Divide by 2
2x/2 = 178/2
x = 89
Answer
x = A = 88
89 - 21 = B =68
