SOLUTION: Find the measure of each angle and isosceles triangle if the measure of each of the base angle is 9° less than four times the measure of the vertex angle.

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Question 1004851: Find the measure of each angle and isosceles triangle if the measure of each of the base angle is 9° less than four times the measure of the vertex angle.
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

An isosceles triangle is a triangle with (at least) two equal sides.
in your case, base angles are same
let's the base angles be alpha and beta, and the vertex angle gamma
if the measure of each of the base angle is 9° less than 4 times the measure of the vertex angle, we have
alpha=4gamma-9
beta=4gamma-9
since alpha%2Bbeta%2Bgamma=180 we have
4gamma-9%2B4gamma-9%2Bgamma=180
9gamma-18=180
9gamma=180%2B18
9gamma=198
gamma=198%2F9
gamma=22
now find alpha and beta
alpha=4gamma-9
alpha=4%2A22-9
alpha=88-9
alpha=79 and beta=79
so, your angles are:79,79, and 22