Step-by-step explanation:
Hey there!
LHS
[tex] = \frac{ \cos(a) }{ \tan(a) } [/tex]
Use tan A = sin A/cosA
[tex] = \cos(a) \times \frac{ \cos(a) }{ \sin(a) } [/tex]
[tex] = \frac{ { \cos(a) }^{2} }{ \sin(a) } [/tex]
Then, Use formula cos²A = 1-sin²A and sinA = √(1-cos²A)
[tex] = \frac{1 - { \sin(a) }^{2} }{ \sqrt{ - { \cos(a) }^{2} } } [/tex]
Proved!
Hope it helps!