Question

If an isosceles triangle with the equal sides of length $b$ and base angle $\alpha <\pi /4$ , then the circumradius R is given by?

• A. $\frac{1}{2}b$cosec $\alpha$
• B. $bcosec$ $\alpha$
• C. $2b$
• D. none of these

Answer 1

The correct option is A $\frac{1}{2}b$cosec $\alpha$

using above formula we can write

$\frac{b}{sin\alpha }=2R\Rightarrow R=b\frac{cosec\alpha }{2}$

Therefore, Correct Answer is $A$