Question

Can you show how to find the solution of number 11 on a unit circle

Answer 1

Step-by-step explanation:

Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because cosine is negative in the second quadrant.

`cos(-3\pi)/(4)`

Use the following property

`cos(-x)=-cosx`
`\begin{gathered} cos(-(3\pi)/(4))=-cos(3\pi)/(4) \\ =-(√(2))/(2) \end{gathered}`

Therefore the value of cosine in the second quadrant is negative

Then, cos (-3π/4) =

`-(√(2))/(2)`