SOLUTION: One angle of an isosceles triangle is twice another angle of the triangle. Which of the following could NOT be an angle of this triangle? A. 18◦ B. 36◦ C. 45◦

Algebra ->  Triangles -> SOLUTION: One angle of an isosceles triangle is twice another angle of the triangle. Which of the following could NOT be an angle of this triangle? A. 18◦ B. 36◦ C. 45◦       Log On


   

Question 286763: One angle of an isosceles triangle is twice another angle of the triangle. Which of the following could NOT be an angle of this triangle?
A. 18◦ B. 36◦ C. 45◦ D. 72◦ E. 90◦
Answer by vleith(2983) About Me  (Show Source):
You can put this solution on YOUR website!
It cannot be 18.
To see this, note that every isosceles triangles will have two angles equal. You are told the third angle is either 1/2 or twice the other two angles.
You also know that every triangle has 180 interior degrees in it.
So 45+45+90 = 180
72+72+36 = 180
Thus only 18 won't work