Trigonometry
posted by Anonymous .
2sin^2(x )+38 cos(x) + 2.6=0

Trigonometry 
GanonTEK
Change Sin^2(x) into 1cos^2(x), substitute it in, tidy it up and you'll get a quadratic of the form
aCos^2(x) + bCos(x) + c = 0
Then let, say, y = Cos(x) then and you get
ay^2 + by + c = 0
which is a more normal quadratic. Solve that for y and put your answer equal to Cos(x). There will be 2 possible values of y probably and 2 possible values for Cos (x) for each value of y. In total, 4 answers.
Respond to this Question
Similar Questions

tigonometry
expres the following as sums and differences of sines or cosines cos8t * sin2t sin(a+b) = sin(a)cos(b) + cos(a)sin(b) replacing by by b and using that cos(b)= cos(b) sin(b)= sin(b) gives: sin(ab) = sin(a)cos(b)  cos(a)sin(b) … 
trig
2sin(x)cos(x)+cos(x)=0 I'm looking for exact value solutions in [0, 3π] So I need to find general solutions to solve the equation. But do I eliminate cos(x), like this... 2sin(x)cos(x)+cos(x)=0 2sin(x)cos(x)= cos(x) 2sin(x) = … 
Precal
I do not understand how to do this problem ((sin^3 A + cos^3 A)/(sin A + cos A) ) = 1  sin A cos A note that all the trig terms are closed right after there A's example sin A cos A = sin (A) cos (A) I wrote it out like this 0 =  … 
Trigonometry
Solve for x: 1. 2sin(2x)+cos(x)=0 2. cos(2x)=2sin(x) 3. tan(x)=2sin(x) 
trigonometry (please double check this)
Solve the following trig equations. give all the positive values of the angle between 0 degrees and 360 degrees that will satisfy each. give any approximate value to the nearest minute only. 1. sin2ƒÆ = (sqrt 3)/2 2. sin^2ƒÆ = … 
URGENT  Trigonometry  Identities and Proofs
Okay, today, I find myself utterly dumbfounded by these three questions  Write a proof for  2/(sqrt(3)cos(x) + sin(x))= sec((pi/6)x) Solve the following equation  2sin(2x)  2sin(x) + 2(sqrt(3)cos(x))  sqrt(3) = 0 Find all solutions … 
Trigonometry
Prove that cos(A+B) + sin(AB) = 2sin(45°+A)cos(45°+B) 
Math (trigonometry)
How do you solve this trig identity problem without factoring? 
trigonometry
2sin^2 A + 5cosA = 4 , Prove that cos A = 1/2 
trigonometry
Solve the equation in the interval [0, 2pi]. 2sin(t)cos(t)cos(t)+2sin(t)1=0 Answer needs to be formatted as x={Insert answers here}pi If the answer is something like pi/6 it simply goes in as 1/6th since pi is already given at the …