<PRE><B>Question 180232</B>
Concepts you should now:
(1) The sum of the three interior angles of a triangle is 180
(2) An isosceles triangle has two sides that measure the same length (called legs) opposite two congruent angles (called based angles)

Therefore

2x + 18 = 180 , where x represents each base angle
2x+18-18=180-18
2x=162
2x/2=162/2
x=81

each base angle measure 81 degrees</PRE>