Question

7sin^2x-5cos^2x=?cosx=-0.1​

Answer 1

Ответ:

Пошаговое объяснение:

7-7cos^2x-5cos^2x+2=0

9-12cos^2x=0

cos^2x=9/12

cos^2x=3/4

cosx=√3/2

x=+-π/6+2πn: n∈ Z как-то так

Answer 2

To find the value of the expression 7sin^2x - 5cos^2x when cos(x) = -0.1, we can use the trigonometric identity:

sin^2x + cos^2x = 1

Rearranging for sin^2x:

sin^2x = 1 - cos^2x

Now, we can substitute the value of cos(x) into this expression:

sin^2x = 1 - (-0.1)^2 sin^2x = 1 - 0.01 sin^2x = 0.99

Now, we can calculate the value of the given expression:

7sin^2x - 5cos^2x = 7(0.99) - 5(-0.1)^2 7(0.99) - 5(0.01) 6.93 - 0.05 6.88

So, when cos(x) = -0.1, 7sin^2x - 5cos^2x is equal to 6.88.