Question

Evaluate Tan5, Tan25, Tan30, Tan65, Tan 85

Answer 1

Tan 5 = tan(90-85) = cot85

Tan 25 = Tan(90-65) = Cot65

Tan5 Tan25 Tan30 Tan 65 Tan85  

⇒ Cot85 Cot 65 Tan30 Tan65 Tan85

⇒ Tan 30 (Since Cot85*Tan85 = 1 and Cot65*Tan65 = 1)

⇒  \frac{1}{ \sqrt{3}}