Add Maths Trigonometric Functions

[Anonymous_want_12A]

Prove the following statement:

Anyone know how to do this question?

[Alex]

Hi, attached is my solution, although I believe there might be an easier way:

Question

\tan A \tan \left(A-60^{\circ}\right)+\tan A \tan \left(A+60^{\circ}\right)+\tan \left(A-60^{\circ}\right) \tan \left(A+60^{\circ}\right)=-3

Solution

[Anonymous_want_12A]

Okay, I understand now, tqvm!