All points on the graph y=9sin(x)cos(x)

[killasnake]

Hi with this question I graphed it on my calculator. But what would be the tangent line of the graph?

Find all points on the graph of y=9sin(x)cos(x) where the tangent line has horizontal.

The tangent of graph is horizontal when

X=_______ +K_______ where k is an integer.

How would I solve this?

 

[stapel]

How would I solve this?

Follow the usual procedure for finding where the derivative is zero: Take the derivative, set it equal to zero, and solve.

Where are you stuck in the process? Please be specific. Thank you.

Eliz.

 

[killasnake]

Sorry about that,
I found the derivative it is 9cos(2x) = 0 but when you say solve. What do you mean? Graphing it?

 

[stapel]

...when you say solve. What do you mean?

By "solve", I mean "solve". For what values of x is cos(2x) equal to zero? A graph might be helpful for reminding you of how the cosine wave works. But you'll still need to provide the exact solution, as you learned back in trigonometry.

Eliz.