Question

Please solve the question attached.

Answer 1

Answer: (hopefully it is right)

Tan A = n Tan B  ---(1)

Sin A = m Sin B  --- (2)

(2) ÷ (1) gives:  CosA = (m/n) CosB    --(3)

From (2)

   Cos² A = 1 - m² Sin²B

                = 1 - m² [1 - cos²B]

                = 1 - m² + m² Cos²B

                = 1 - m² + n² Cos²A      using (3)

=> (n²-1) Cos²A = m² -1 

=>  Cos²A = (m² - 1) / (n² - 1)

Hence Proved

HOPE IT HELPS