Find the area of a triangle whose sides are 29 cm, 20 cm and 21 cm.

Consider a = 29 cm, b = 20 cm and c = 21 cm

We know that,

Semi perimeter (s) = $\dfrac{(a + b + c)}{2}$

Substituting the values we get,

s = $\dfrac{(29 + 20 + 21)}{2} = \dfrac{70}{2}$ = 35 cm.

Area of triangle = $\sqrt{s(s - a)(s - b)(s - c)}$

Substituting values we get,

$A = \sqrt{35(35 - 29)(35 - 20)(35 - 21)} \\[1em] = \sqrt{35 \times 6 \times 15 \times 14} \\[1em] = \sqrt{44100} \\[1em] = 210 \text{ cm}^2.$

Hence, area of triangle = 210 cm².