Home › TS EAPCET (Engineering) › Mathematics › Trigonometry: Trigonometric Ratios upto Transformations › If cos θ = 3/5, what is cos 2θ?
If cos θ = 3/5, what is cos 2θ?
A9/25
B24/25
C-7/25
D7/25
Answer & Solution
Correct answer: C. -7/25
cos 2θ = 2cos²θ − 1 = 2 × 9/25 − 1 = −7/25.
Related questions
If cos θ = 2/3, the value of cos 2θ is:The minimum value of sin x − cos x over all real x is:In the third quadrant, which pair of ratios is positive?If sin θ = 3/5 with θ acute, then cos 2θ equals:For acute angles A and B with sin A = 3/5 and cos B = 5/13, sin(A + B) is:Given tan A = 3 and tan B = 1/2, what is tan(A − B)?If tan A = 1/2 and tan B = 1/3, then A + B in degrees is:The product of sin(kπ/6) for k = 1, 2, 3, 4, 5 equals: