Question

$\frac{cos{10}^{\circ }+sin{10}^{\circ }}{cos{10}^{\circ }-sin{10}^{\circ }}$ is equal to

• A. $tan{55}^{\circ }$
  
• B. $cot{55}^{\circ }$
  
• C. $-tan{35}^{\circ }$
  
• D. $-cot{35}^{\circ }$
  

Answer 1

The correct option is A $tan{55}^{\circ }$


$\frac{cos{10}^{\circ }+sin{10}^{\circ }}{cos{10}^{\circ }-sin{10}^{\circ }}$
$=\frac{1+tan{10}^{\circ }}{1-tan{10}^{\circ }}$
$=\frac{tan{45}^{\circ }+tan{10}^{\circ }}{1-tan{45}^{\circ }\times tan{10}^{\circ }}$
$=tan{55}^{\circ }$