Question

if perimeter of an isosceles triangle is 11cm and its unequal side is 5cm. then find its area.

Answer 1

Perimeter = Sum of all sides
Let the equal side be x
$5 + 2x = 11 \\ 6 = 2x \\ x = 3$
Area of a ∆ =
$\sqrt{s(s - a)(s - b)(s - c)} \\ \sqrt{ \frac{11}{2} ( \frac{11}{2} - 5)( \frac{11}{2} - 3)( \frac{11}{2} - 3) } \\ \sqrt{ \frac{11}{2}( \frac{1}{2} )( \frac{5}{2} )( \frac{5}{2} )} \\ \sqrt{ \frac{275}{16} } \\ \frac{ \sqrt{275} }{4}$
5√11/4