Trig
posted by Gina .
If sin^2X=A what is an algebraic expression in A for cos(2X). I have no idea where to even begin with this!

You should have come across the identity
cos 2x = 1  2sin^2 x
so
cos 2x = 1  A^2
Respond to this Question
Similar Questions

trigonometry HELP pleasE!
these must be written as a single trig expression, in the form sin ax or cos bx. a)2 sin 4x cos4x b)2 cos^2 3x1 c)12 sin^2 4x I need to learn this!! if you can show me the steps and solve it so I can learn I'd be grateful!!! 1) apply … 
trig
Reduce the following to the sine or cosine of one angle: (i) sin145*cos75  cos145*sin75 (ii) cos35*cos15  sin35*sin15 Use the formulae: sin(a+b)= sin(a) cos(b) + cos(a)sin(b) and cos(a+b)= cos(a)cos(b)  sin(a)sin)(b) (1)The quantity … 
algebra
Can someone please help me do this problem? 
TRIG!
Posted by hayden on Monday, February 23, 2009 at 4:05pm. sin^6 x + cos^6 x=1  (3/4)sin^2 2x work on one side only! Responses Trig please help!  Reiny, Monday, February 23, 2009 at 4:27pm LS looks like the sum of cubes sin^6 x + cos^6 … 
trig
The expression 4 sin x cos x is equivalent to which of the following? 
trig 30
For csc^2 A1/cot A csc A, what is the simplest equivalent trig expression? 
trig 26
simplify to a constant or trig func. 1. sec ²utan ²u/cos ²v+sin ²v change expression to only sines and cosines. then to a basic trig function. 2. sin(theta)  tan(theta)*cos(theta)+ cos(pi/2  theta) 3. (sec y  tan y)(sec y + … 
calculus/Trig
Suppose you wish to express sin(3t) in terms of sint and cost. Apply the sum formula to sin(3t) = sin(t+2t) to obtain an expression that contains sin(2t)=sin(t+t) and cos(2t)=cos(t+t). Apply the sum formulas to those two expressions. … 
pre calc trig check my work please
sin x + cos x  = ? sin x sin x cos x  +  = sin x sin x cos x/sin x = cot x this is what i got, the problem is we have a match the expression to the equation work sheet and this is not one of the answers. need 
PreCal (Trig) Help?
The following relationship is known to be true for two angles A and B: cos(A)cos(B)sin(A)sin(B)=0.957269 Express A in terms of the angle B. Work in degrees and report numeric values accurate to 2 decimal places. So I'm pretty lost …