Question

If ${\sin }^{-1}(\sin 4)+{\cos }^{-1}(\cos 8)+{\tan }^{-1}(\tan 6)+{\cot }^{-1}(\cot 10)=a+b\pi$ then $(a+b)$ equals

• A. 26
• B. 14
• C. 12
• D. 10

Answer 1

Answer: (B)

$\pi -4+8-2\pi +6-2\pi +10-3\pi =20-6\pi$
$\therefore a=20;b=-6$
$\Rightarrow a+b=14.$