Pre-Calculus

posted by .

If θ represents an angle such that sin2θ = tanθ - cos2θ, then sin θ - cosθ =

A. -√2
B. 0
C. 1
D. 2√2

What equation can I use to solve this problem?

  • Pre-Calculus -

    sin2A + cos2A - sinA/cosA = 0
    2sinAcosA + 1 - 2sin^2 A - sinA/cosA = 0
    2sinAcos^2 A + cosA - 2sin^2 A cosA - sinA = 0
    2sinAcosA(cosA - coA) + (cosA - sinA) =
    (cosA - sinA)(2sinAcosA + 1) = 0
    cosA - sinA = 0 or ......

    got it! That's all they asked for.
    cosA - sinA = 0

  • Pre-Calculus -

    Oh...okay. Thanks for the help.

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Math - Calculus

    The identity below is significant because it relates 3 different kinds of products: a cross product and a dot product of 2 vectors on the left side, and the product of 2 real numbers on the right side. Prove the identity below. | a …
  2. math

    if cosθ=2/3 and tanθ<0 find the exact value sin(θ-5π/3) sin2θ cos2θ cos(θ/2) can some1 please help me?
  3. trigonometry

    if cosθ=2/3 and tanθ<0 find the exact value sin(θ-5π/3) sin2θ cos2θ cos(θ/2) can some1 please help me?
  4. Trigonometry

    Which of the following is equivalent to 1 − cos 2 θ/cos 2 θ?
  5. math trigono

    1. If tanθ = –√3 , what is the value of cot ?
  6. trig

    An object Is propelled upward at an angle θ, 45° < θ<90°, to the horizontal with an initial velocity of (Vo) feet per second from the base of a plane that makes an angle of 45° with the horizontal. If air resistance …
  7. Math (Trigonometry)

    θ is an acute angle such that tan(θ) = 12. What is the value of 5√5⋅(sinθ+cosθ)?
  8. Trigonometry

    There are four complex fourth roots to the number 4−4√3i. These can be expressed in polar form as z1=r1(cosθ1+isinθ1) z2=r2(cosθ2+isinθ2) z3=r3(cosθ3+isinθ3) z4=r4(cosθ4+isinθ4), …
  9. Math (Trigonometry)

    θ is an acute angle such that tan(θ)=1/4. What is the value of 17√17*(sinθ+cosθ)?
  10. Precalc/Trig

    Sorry there are quite a few problems, but I just need to know if these are correct (and if they aren't, where I went wrong): 1. Solve these equations. tanθ = -√3 θ = 2π/3 + kπ θ = 5π/3 + kπ …

More Similar Questions