trigonometry compund angle formula

**greghunter** · September 9th 2009, 12:22 PM

Prove that $sec^2 \theta + cosec^2 \theta \equiv 4cosec^2 2\theta$

Really not sure about using the compound angle formula. Thanks for any help

**red_dog** · September 9th 2009, 01:00 PM

$\sec^2\theta+\csc^2\theta=\frac{1}{\cos^2\theta}+\ frac{1}{\sin^2\theta}=\frac{\sin^2\theta+\cos^2\th eta}{\sin^2\theta\cos^2\theta}=$

$=\frac{1}{\sin^2\theta\cos^2\theta}=\frac{4}{4\sin ^2\theta\cos^2\theta}=\frac{4}{\sin^22\theta}=4\cs c^22\theta$

**greghunter** · September 10th 2009, 10:55 AM

Thanks, I managed to work out what to do in the end. Can anyone tell me what you would do to find $\theta$ ?

**pacman** · September 10th 2009, 06:56 PM

aaahh, you post this as a trigonometric equation? i thought it was an identity as as solved by red_dog, YOUR post is an identity . . . .

Thread: trigonometry compund angle formula

LinkBack

Thread Tools

Display

trigonometry compund angle formula

Finding the values

Similar Math Help Forum Discussions

Trigonometry - Angle Of Elevation

Trigonometry: Using Double Angle Formula for Tangent to Prove an Equality

Finding angle/ Double angle formula

Trigonometry - Half angle??

Trigonometry; looking for an angle! Help!

Search Tags