Problem

In a

\Delta ABC

, if

a = 13

b = 14

and

c = 15

, then

\angle A

is equal to (All symbols used have their usual meaning in a triangle.) a.

\sin^{-1} \frac{4}{5}

\sin^{-1} \frac{3}{5}

\sin^{-1} \frac{3}{4}

\sin^{-1} \frac{2}{3}