What is cot²(sec^-1 2) + tan² (cosec^-1 3) equal to ?

In a triangle ABC $\rm \frac{a}{\cos A}=\frac{b}{\cos B}=\frac{c}{\cos C}$ What is the area of the triangle if a = 6 cm?

The roots of the equation 7x² - 6x + 1 = 0 are tan α and tan β, where 2α and 2β are the angles of a triangle. Which one of the following is correct?

In a triangle ABC, ∠A = 75° and ∠B = 45°. What is 2a - b equal to?