SOLUTION: Hi, please help with this problem. A triangle with angles 40, 40, and 100 has a perimeter of 20cm. Find the length of each side of the triangle. I know that it is an isosceles tri

Algebra ->  Triangles -> SOLUTION: Hi, please help with this problem. A triangle with angles 40, 40, and 100 has a perimeter of 20cm. Find the length of each side of the triangle. I know that it is an isosceles tri      Log On


   

Question 1035801: Hi, please help with this problem. A triangle with angles 40, 40, and 100 has a perimeter of 20cm. Find the length of each side of the triangle.
I know that it is an isosceles triangle and perimeter is sum of sides so formula would be perimeter =2a+b or 20=2a+b.
How do I proceed as it seems to have too little info?
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
A triangle with angles 40, 40, and 100 has a perimeter of 20cm. Find the length of each side of the triangle.
I know that it is an isosceles triangle and perimeter is sum of sides so formula would be perimeter =2a+b or 20=2a+b.
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Make a similar triangle with short sides of a = 10 & b = 10 (or any length).
Find the 3rd side, c, using the Cosine Law.
c =~ 14.7433
Perimeter = 34.7433
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"Scale it" by 20/34.7433
The short sides are 10*(20/34.7433) = 5.7565
The long side is 8.4867