Find the radian measures 40⁰ 20'

Find the values of cos x and tan x if \(\sin x=-\frac{3}{5}\) and \(\pi < x < \frac{3\pi}{2}\)

Prove that \(\frac { 1+sinx-cosx }{ 1+sinx+cosx } =tan\frac { x }{ 2 } \) .

In a ΔABC if a = 3, b = 5 and c = 7, find cos A and cos B.

Prove that \({ tan }^{ -1 }\left( \frac { 1 }{ 7 } \right) +{ tan }^{ -1 }\left( \frac { 1 }{ 13 } \right) ={ tan }^{ -1 }\frac { 2 }{ 9 } \)