Hi, all help is much appreciated. (Nod)

for this question, I've been trying to figure it out.

h = -10 cos (πt/15) + 11

where

h = height (m)

t = time in seconds

if t = 10

i know one way is to plot the graph and find the point but my graph isn't accurate enough and i don't have the proper calculator.

how do i find h.

Thanks.