Question

Can someone explain to me how to solve this problem?

Answer 1

@mathmale

Answer 2

it appears, from those marks, that the two longer sides of the triangle are of the same length. That makes it an "isosceles" triangle. If that's the case, then the unmarked angle inside the triangle has the same measure as does the angle x. Follow me so far?

Answer 3

yes I follow

Answer 4

so the unmarked angle would be y,

Answer 5

The only given angle is OUTSIDE the triangle, isn't it? What do you think is the measure of angle x, and why?

No, the unmarked angle would not be y. What other name could it have, and why?

Answer 6

So I think that the angle x would be 80 because the other angle is 100 degrees, and a straight line equals 180.

Answer 7

Exactly right. Congrats. And therefore, the unmarked angle would have what measure? Hint again: This is an isosceles triangle.

Answer 8

So this is how the triangle looks right now