# I've been trying so hard to solve this exercise but I honestly can't. It would be so nice of you if you can help me?. Thank you very much!

Sep 25, 2017

see explanation

#### Explanation:

a. ...start by dividing both sides by 7:

$\frac{h}{7} = \cos \left(\frac{\pi}{3} t\right)$

now take the arc cosine of each side:

${\cos}^{-} 1 \left(\frac{h}{7}\right) = \frac{\pi}{3} t$

now multiply each side by $\frac{3}{\pi}$:

$\frac{3 \left({\cos}^{-} 1 \left(\frac{h}{7}\right)\right)}{\pi} = t$

For b and c, you can just plug in values 1,3,5, and -1,-3, -5.

I'll do the first couple:
for height 1:
$\frac{3 \left({\cos}^{-} 1 \left(\frac{1}{7}\right)\right)}{\pi} = t$

$= 3 \frac{{\cos}^{-} 1 \left(0.143\right)}{\pi}$

$= 3 \frac{1.43}{\pi}$

$= 1.36$

for height 3:
$\frac{3 \left({\cos}^{-} 1 \left(\frac{3}{7}\right)\right)}{\pi} = 1.08$

...and so on.

GOOD LUCK!