View Full Version : cos^2 + tan^2(cos^2)=1
vericacnae
Mar 8, 2012, 09:08 PM
^2 means to (second power)
I would really love to know exactly how to do it I'm completely confused
vericacnae
Mar 8, 2012, 09:09 PM
The directions say verify each identity
ebaines
Mar 9, 2012, 07:02 AM
Remember that tan(x) = sin(x)/cos(x), so if you make that substitution you get:
\cos^2x + ( \frac {\sin^2x}{\cos^2x} ) \cos^2x = \cos^2x + \sin^2x
Now you apply the basic identity
\cos^2x + \sin^2x = 1
In general for proving trig identities like this you should always replace any tangent, cortangent, secant and cosecant functions with their sine and cosine equivalents, and if you remember a few key identites it is usually pretty straight forward to work out.
Stratmando
Mar 10, 2012, 05:10 AM
ebaines is exceptional at math among other things, will help greatly.
I googled your formula and found this, seems helpful:
Trigonometric Identities (http://www.math.com/tables/trig/identities.htm)