Question

Prove that tan13a − tan9a− tan3a = tan13a.tan9a.tan3​a

Answer 1

Answer:

Given a = 0

or, 13a–9a–3a = 0

or, tan(13a–9a–3a) = tan0

From the formula of tan(a–b–c), we got

(tan13a–tan9a–tan3a–tan13a.tan9a.tan3a)

1+tan13a.tan9a–tan9a.tan3a+tan3a.tan13a

= 0

or, tan13a–tan9a–tan3a–tan13a.tan9a.tan3a = 0

or, tan13a–tan9a–tan3a = tan13a.tan9a.tan3a (proved)