Solve for x:
(4 x + 1)^2 = 4 x^2 + (4 x - 1)^2
Expand out terms of the right hand side:
(4 x + 1)^2 = 20 x^2 - 8 x + 1
Subtract 20 x^2 - 8 x + 1 from both sides:
-1 + 8 x - 20 x^2 + (4 x + 1)^2 = 0
Expand out terms of the left hand side:
16 x - 4 x^2 = 0
Factor x and constant terms from the left hand side:
-4 x (x - 4) = 0
Divide both sides by -4:
x (x - 4) = 0
Split into two equations:
x - 4 = 0 or x = 0
Add 4 to both sides:
x = 4. The sides of the triagle are: [2x4=8, 4x4 - 1 =15, 4x4 +1=17]. Perimeter =8 + 15 + 17=40 cm
