Help with Trig Question: How Many Times Does Shantaro Hit Ground in 5 Seconds?

[Sebastian999]

Homework Statement

The height (h) in cm of Shantaro's pogo stick as he jumps in (s) seconds is roughly modeled by h(s)= sin^(2)4x+2sin4x+1
a) how many times does shantaro hit the ground in the first five seconds

Homework Equations

The Attempt at a Solution

i don't even know where to start :(
i tried with g.calc but i need to do it algerbraically

 

[CompuChip]

Note that when he hits the ground, h(s) = 0. So you are asked to find all values 0 < s < 5 for which h(s) = 0.

Now, assuming you meant h(s)= sin²(4s)+2sin(4s)+1, you can start by defining y = sin(4s) and rewriting s to y.

 

[Дьявол]

Note that when he hits the ground, h(s) = 0. So you are asked to find all values 0 < s < 5 for which h(s) = 0.

Now, assuming you meant h(s)= sin²(4s)+2sin(4s)+1, you can start by defining y = 4s and rewriting s to y.

It would be better to substitute sin(4s)=y, so he will come up with quadratic equation.

Regards.

 

[CompuChip]

Whoops, that's what I meant of course. Nice catch.