7cos^2 (4X) + 7sin^2 (4x)

Question

solve with only trig identities, no calc

Answer 1

7cos²(4x) + 7 sin²(4x)

 

Factor out the 7:

 

7*(sin²(4x) + cos²(4x))

 

Since sin²(θ) + cos²(θ) = 1   (let θ = 4x)

 

7*(1) = 7

Answer 2

7cos^2 (4X) + 7sin^2 (4x)

we can factorize and we have:

7(cos^2 (4X) + sin^2 (4x))

But sin²(4x) + cos²(4x) = 1 no matter which angle is (4x)

Then the answer is 7

Answer 3

factor out the 7

 

7 (cos²(4x) + sin²(4x))               cos²(Y) + sin²(Y) = 1

 

7(1) = 7