trig

[carebear]

I have a few trig questions that I am unsure of. can you please help?

1.What is the maximum value of 3(cos^2(x) - sin^2(x))? I believe the answer is 3 when I look at the graph. Is there a way I can do this question without graphing?

2. On the unit circle the coordinates of P(theta) are (0.588, 0.809). Find the coordinates of P(2theta). Please help.

 

[Deleted member 4993]

I have a few trig questions that I am unsure of. can you please help?

1.What is the maximum value of 3(cos^2(x) - sin^2(x))? I believe the answer is 3 when I look at the graph. Is there a way I can do this question without graphing?

Use

cos[sup:10kafc3c]2[/sup:10kafc3c](x) - sin[sup:10kafc3c]2[/sup:10kafc3c](x) = cos(2x)

2. On the unit circle the coordinates of P(theta) are (0.588, 0.809). Find the coordinates of P(2theta).

sin(?) = 0.809

cos(?) = 0.588

Please share your work with us, indicating exactly where you are stuck - sothat we may know where to begin to help you.

Please help.

 

[carebear]

i am not sure if this is correct, but this is what I started with.....

I found that using tangent(2nd tan .809/ .588), theta = 0.942, so 2theta = 2 times 0.942 which equals 1.884, but then did not know how to find the sin and cos values for that point on the unit circle. Have I started correctly or am I way off track?