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
In a triangle with sides a = 5, b = 7, and included angle C = 60°, what is side c?
Answer: √39
By the cosine rule: c² = 25 + 49 - 2(5)(7)cos60° = 74 - 35 = 39, so c = √39.
Which of the following is the correct expression for the area of a triangle with sides a, b and included angle C?
Answer: (1/2)ab·sin(C)
The area formula using two sides and the included angle is Area = (1/2)ab·sin(C).
What is the value of arcsin(sin(5π/6))?
Answer: π/6
sin(5π/6) = 1/2, and arcsin returns values in [-π/2, π/2], so arcsin(1/2) = π/6.
If tan(x) = -√3 and x ∈ [π/2, π], what is x?
Answer: 2π/3
tan(x) = -√3 and x is in Q2, so x = π - π/3 = 2π/3.
Which identity correctly represents cos²(x) in terms of cos(2x)?
Answer: (1 + cos(2x))/2
From cos(2x) = 2cos²x - 1, rearranging gives cos²x = (1 + cos2x)/2.
Given that sin(A) = 5/13 and cos(B) = 4/5, with A and B both in the first quadrant, find sin(A + B).
Answer: 56/65
cos A = 12/13, sin B = 3/5; sin(A+B) = sinAcosB + cosAsinB = (5/13)(4/5) + (12/13)(3/5) = 20/65 + 36/65 = 56/65.
What is the number of solutions to sin(2x) = 0.5 in the interval [0, 2π]?
Answer: 4
Let u = 2x ∈ [0, 4π]; sin(u) = 0.5 has 4 solutions: π/6, 5π/6, π/6+2π, 5π/6+2π.