Answer
Each of the long sides $= 86$ cm. If both were added, they would be $172$ cm long.
Work Step by Step
1. Find the missing angle of the right angled triangle (Isosceles triangle is made up of 2 right angled triangles)
Let $x =$ the unknown angle of the right angled triangle
$180 = 17 + 90 + x$
$180 = 107 + x$
$x = 73˚$
2. Find the missing length of the horizontal length
$\frac{a}{sin(73)} = \frac{25}{sin(17)}$
$a = \frac{25sin(73)}{sin(17)}$
$a = 81.77...$ cm
3. Find the lengths of the equal sides, Let $c =$ the length
$a^{2} + b^{2} = c^{2}$
$(81.77..)^{2} + (25)^{2} = c^{2}$
$c = \sqrt (6686.548032 + 625)$
$c = 85.5$ cm
$c = 86$ cm
