The altitude drawn to the base of an isosceles triangle is 8 cm and the perimeter is 32 cm. Find the area of the triangle.

A 24

B 48

C 60

D  72

Solution

Correct Answer: Option B

Let ABC be the isosceles triangle and AD be the altitude 

Let AB = AC = x. Then, BC = (32 - 2x). 

Since, in an isosceles triangle, the altitude bisects the base,
so BD = DC = (16 - x).
In triangle ADC , \(\left(AC\right)^2=\left(AD\right)^2+\left(DC\right)^2\)

\(\Rightarrow x^2=\left(8\right)^2+\left(16-x\right)^2\Rightarrow x=10\)

BC = (32- 2x) = (32 - 20) cm = 12 cm. 

Hence, required area = \(\frac12\ast BC\ast AD=\frac12\ast12\ast8=48cm^2\)

 

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