Question

3. Let sin 21 = 0.358. What is the value of x for cos x=0.358?

Answer 1

`\cos(69)`

Explanation:

We will use the co-function identity for sine, where:

`\sin(x)=\cos(90-x)`

Since sin(21)=0.358=cos(x). This means that:

`21=90-x`

Solve for x. Add x to both sides:

`x+21=90`

Subtract 21 from both sides:

`x=69\textdegree`

Hence:

`\sin(21)=\cos(69)\approx0.358`