Question

The length of each two equal sides of an isosceles triangle is 4 cm less than 2 times the length if the third side. Find the dimensions if the the perimeter is 57

Answer 1

We don't know what the length of the 3rd side is, so we'll call this length "x"

We do know the other 2 side lengths. They are each 3x - 4.

 

If all three side lengths gives us a perimeter of 55 then 

all we have to do is add up all three sides. This gives 

us an equation.....

 

3x - 4  +  3x - 4  +  x = 55   Now just solve...

 

7x - 16 = 55

7x -16 + 16 = 55 + 16

7x = 63

7x/7 = 63/7

x = 9

 

This value of "x" is the length of the third side. If we 

substitute it into the expression for the other two sides, 3x - 4, 

we get....

 

3x - 4

3(9) - 4

27 - 4

23

 

And to check....

9 + 23 + 23 = 55

55 = 55  YEAH!!  You did it!

ok u got the answer feel h