Answer:
I remember isosceles from the I sounding like eye and we have 2 eyes.
An isosceles triangle has two sides that are the same. We know the sides are the same because of the picture and if we subtract the angles 80 + 50 = 130 180-130=50 so that means that both A and C are 50 degrees so the triangle is isosceles.
My grammar isn't the best so you can make some edits but overall basically there are two sides that are the same.
Explanation: