An isosceles triangle has a perimeter of 8.5 cm. a second isosceles triangle, whose base is equal to that of the first but whose legs are twice as long of the first, has a perimeter of 15.5 cm. find the lengths of the sides of each triangle.
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So you have length
l=legs and b=base
the first perimeter is 2l+b=8.5 since there are 2 legs
the second perimeter is 4l+b=15.5 since the legs are now 2l long instead of l
subtract the top problem from the bottom problem
(4l+b)-(2l+b)=15.5-8.5
2l=7 so l=3.5
if l=3.5 and 2l+b=8.5, 7+b=8.5, so b=1.5
check by plugging it into the second perimeter
4(3.5)+1.5=15.5-->14+1.5=15.5      it's correct yay!

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