# Transformations of Trigonometric Graphs

• Mar 27th 2010, 01:18 PM
Transformations of Trigonometric Graphs
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.
• Mar 27th 2010, 01:32 PM
mathemagister
Quote:

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.

Substitute 10 for t in the function:

$\displaystyle h = -10 \cos{\frac{\pi (10)}{15}} + 11$

$\displaystyle h = -10 \cos{\frac{2\pi}{3}} + 11$

You can calculate $\displaystyle \cos{\frac{2\pi}{3}}$ using the unit circle (or simply with a calculator). You should get -0.5 as the answer.

$\displaystyle h = -10(-0.5) + 11 = 16$