Exercise 8.2

$\sin \left(\mathrm{A}+\mathrm{B}\right)=\sin \mathrm{A}+\sin \mathrm{B}$

$\cot \mathrm{A}$ is not defined for $\mathrm{A}=0°$.

Evaluate $\frac{\sin 18°}{\cos 72°}$.

Evaluate :$\frac{\tan 26°}{\cot 64°}$

Evaluate $\cos 48°-\sin 42°$.

Evaluate the following trigonometric ratio:

$\mathrm{cosec} 31°-\sec 59°$

Show that:
$\cos {38}^{\mathrm{o}}\cos {52}^{\mathrm{o}}-\sin {38}^{\mathrm{o}}\sin {52}^{\mathrm{o}}=0$

If $\tan \mathrm{A}=\cot \mathrm{B}$, prove that $\mathrm{A}+\mathrm{B}=90°.$