Question

An isosceles triangle has a base
118 mm long and two equal sides
are each 143 mm long. Calculate
the area of the traingle.​

Answer 1

Answer:

As we know that, the area of an isosceles triangle is given as-

A= 1/2×base×Altitude

Now,

Let ABC be the given triangle.

Therefore,

AB=AC=143mm

BC=118mm

BD=CD= 1/2BC=59mm

Now in △ABD

∠ADC=90°[∵AD⊥BC]

By pythagoras theorem,

AC^2=AD^2+CD^2

(143)^2=AD^2+(59)^2

⇒AD^2=20449−3481

⇒AD=√16968=130.26mm

Therefore,

Area of△ABC=1/2×BC×AD

=1/2×118×130.26=7685.4mm^2

Hence the correct answer is 7685.34mm^2