Question

If sin t = 4/5 and t is in the first quadrant, find cos(2t)

Answer 1

-7/25

Explanation:

We can calculate the value of t, as follows:

`\begin{gathered} \sin t=(4)/(5) \\ t=\arcsin \mleft((4)/(5)\mright) \\ t=53.13\text{\degree} \end{gathered}`

Now, we calculate the cosine of 2t, like this:

`\begin{gathered} \cos (2\cdot53.13) \\ \cos (106.26)=-0.28=-(7)/(25) \end{gathered}`