Trigonometry Flashcards
7 cards from real TMUA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Trigonometry flashcards as text
What is the value of cos(A - B) if sin(A) = 3/5, cos(B) = 5/13, and both A and B are acute?
Answer: 56/65
cos A = 4/5, sin B = 12/13; cos(A-B) = cosAcosB + sinAsinB = (4/5)(5/13)+(3/5)(12/13) = 20/65+36/65 = 56/65.
Which of the following is a solution to cos(2x) + cos(x) = 0 in [0, 2π]?
Answer: x = π/3
Substituting 2cos²x - 1 + cosx = 0 gives (2cosx - 1)(cosx + 1) = 0, so cosx = 1/2 → x = π/3.
The graph of y = sin(x) is translated π/4 to the right. What is the new equation?
Answer: y = sin(x - π/4)
A rightward shift by c replaces x with x - c, giving y = sin(x - π/4).
What is the exact value of sin(3π/4)?
Answer: √2/2
sin(3π/4) = sin(π - π/4) = sin(π/4) = √2/2.
Which of the following identities is INCORRECT?
Answer: sin²x + cos²x = 2
The Pythagorean identity is sin²x + cos²x = 1, not 2; the other three identities are correct.
A right triangle has hypotenuse 10 and one angle of 30°. What is the length of the side opposite the 30° angle?
Answer: 5
The side opposite 30° = hypotenuse × sin(30°) = 10 × 0.5 = 5.
For f(x) = 2cos(x/2), what is the period?
Answer: 4π
The period of cos(kx) is 2π/k; with k = 1/2 the period is 2π/(1/2) = 4π.