If the square of the hypotenuse of an isosceles right triangle is 98cm², find the length of each side.

Suppose the length of each of two equal sides of an isosceles triangle is a cm.
Length of square of hypotenuse = $98 {\mathrm{cm}}^2$
So according to the Pythagoras theorem we have;
$$\begin{gathered} a^2+a^2 = 98 \\ \Rightarrow 2a^2 = 98 \\ \Rightarrow a^2 = \frac{98}{2} = 49 \\ \Rightarrow a = \sqrt{49} = 7 \end{gathered}$$
Therefore length of each equal side is 7 cm.