Answer:
Step-by-step explanation:
As we can see, this triangle has 2 equal sides in length, which makes it an isosceles triangle. As the Base Angles Theorem states, the base angles of an isosceles triangle are congruent. In this case, angles a and b are the base angles. We now know they are both congruent, so we'll mark them both as a. Next, we notice that the measure of the other angle is 122°. We also know that the sum of all of the angle measures in a triangle is 180°. Using algebra and what we know so far, we can write this equation:
122°+a+a=180°.
When we solve for a, we get:
122°+2a=180° (add a and a)
2a=58° (subtract 122 from both sides)
a=29°
Since we know a=b, b=29°.
