Question

find the area of triangle in which its perimeter is 42cm two sides of it 10cm and 18cm​

Answer 1

Answer:

1. Perimeter of triangle  = a + b + c

42 = 10 + 18 + c

42 = 28 + c

42 - 28 = c

14 = c

1. Area of triangle = using heron's formula

$\sqrt{s (s - a) + (s - b) + (s - c)}$ where s = perimeter / 2

$\sqrt{2 1 (21 - 18) (21 - 14) (21 - 10)$

$\sqrt{ 21 * 3 * 7 * 11}$

$\sqrt{7 * 7* 3 * 3 * 11}$

7 * 3 $\sqrt{11}$

21$\sqrt{11}$ cm ²