Answer:
see explanation
Step-by-step explanation:
Using the trigonometric identities
• tanx = 
• sin²x + cos²x = 1 ⇒ sin²x = 1 - cos²x
Consider the left side

=
- 
= 1 - cos²x
= sin²x = right side ⇒ verified
Answer: C
Step-by-step explanation: Hope this help :D