Question

Which fundamental identity is used in the second step of proof?

Answer 1

Answer: trigonometric identities

1 C sin^2

2 B csc x(csc x-1)

3 D 1-sin theta/ csc theta

4 D tan x sin x

5 A cos x cot2 x

Answer 2

C) sin^2(Ф) + cos^2(Ф) = 1

Explanation:

sin^2(Ф) - cos^2(Ф)sin^2(Ф) = sin^4(Ф)

LHS = sin^2(Ф) - cos^2(Ф)sin^2(Ф)

Step 1: sin^2(Ф) [ 1 - cos^2(Ф)]

Now we use the identity sin^2(Ф) + cos^2(Ф) = 1 because sin^2(Ф) = 1- cos^2(Ф)

Step 2: Using the above identity

sin^2(Ф) (sin^2(Ф)) = sin^4 (Ф)

Answer: C) sin^2(Ф) + cos^2(Ф) = 1

Hope this will helpful.

Thank you.