You are Here: Home >< Maths

C3 Trig watch

1. Hi, i ma having trouble with the questions below, if anyone could help that would be really useful. Is there an easy way to do them.....i find them really tricky! (i especially struggle on the proofs!)

1. Prove that tanθ +cotθ = 2 cosec 2θ

2. Solve by getting the exact answers in terms of π, 2(1- cos 2θ) = tan θ

3. Express sin^2θ in the form a + b cos 2θ, where a and b are constants.

4. Solve the equation 3 – 3 cos 2θ = 2 cosec θ, giving all solutions in radians in the interval 0 < θ < 2π

Thanks
2. 1. think about sin^2+cos^2 = 1 and sin2x=2sinxcosx... that made it possible for me to solve it...
3. Q1:

TSR's LaTeX system is crap... Those silly floating twos are supposed to be exponents, but for some reason decided they'd be happier riding on top of their trig functions instead of squaring them.
4. (Original post by Dez)
Q1:TSR's LaTeX system is crap... Those silly floating twos are supposed to be exponents, but for some reason decided they'd be happier riding on top of their trig functions instead of squaring them.
Thanks a lot
5. (Original post by nota bene)
1. think about sin^2+cos^2 = 1 and sin2x=2sinxcosx... that made it possible for me to solve it...
thanks for the help
6. 3. Express sin^2θ in the form a + b cos 2θ, where a and b are constants.
cos 2θ = 1 - 2sin²θ

Re-arranging:

2sin²θ = 1 - cos2θ

sin²θ = 1/2 - (cos2θ)/2

So a = 1/2, b = -1/2.

Hope this helps,

~~Simba
7. (Original post by Simba)
cos 2θ = 1 - 2sin²θ

Re-arranging:

2sin²θ = 1 - cos2θ

sin²θ = 1/2 - (cos2θ)/2

So a = 1/2, b = -1/2.

Hope this helps,

~~Simba
thanks for that - just looking at you signature - that is amazing getting 100 in all modules
8. 4. Solve the equation 3 – 3 cos 2θ = 2 cosec θ, giving all solutions in radians in the interval 0 < θ < 2π

The root 3 is the cubic root of 3 not 3root3

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: October 16, 2006
Today on TSR

10,400 people unaware they have HIV

Have you been tested?

University open days

• University of Roehampton
Sat, 17 Nov '18
• Edge Hill University
Faculty of Health and Social Care Undergraduate
Sat, 17 Nov '18
• Bournemouth University
Sat, 17 Nov '18
Poll
Useful resources

Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

How to use LaTex

Writing equations the easy way

Study habits of A* students

Top tips from students who have already aced their exams

Chat with other maths applicants