Question: If for an isosceles triangle the length of each equal side is a units and that of the third side is b units, then its area will be
Options:
A) $ \frac{a}{2}\sqrt{2a^{2}-b^{2}}sq,units $
B) $ \frac{b}{2}\sqrt{a^{2}-2b^{2}},sq,units $
C) $ \frac{a}{4}\sqrt{4b^{2}-a^{2}}sq,units $
D) $ \frac{b}{4}\sqrt{4a^{2}-b^{2}}sq,units $
Show Answer
Answer:
Correct Answer: C
Solution:
- By Heron’s formula,
Area of $ \Delta =\sqrt{s,(s-a)(s-b)(s-c)} $ and $ s=\frac{a+2b}{2} $
$ \Delta =\sqrt{\frac{a+2b}{2}( \frac{a+2b}{2}-a )( \frac{a+2b}{2}-b )( \frac{a+2b}{2}-b )} $ $ =\sqrt{( \frac{a+2b}{2} )( \frac{2b-a}{2} )(a/2)(a/2)} $
$ =\frac{a}{2}\sqrt{\frac{4b^{2}-a^{2}}{4}}=\frac{a}{4}\sqrt{4b^{2}-a^{2}} $