NBT Mathematics: Trigonometry Flashcards

Which statement about the graph of y = cos x is true?

Answer: It is an even function symmetric about the y-axis

Cosine is an even function because cos(−x) = cos x, making its graph symmetric about the y-axis.

Given that cos 2θ = 1 − 2sin²θ and sin θ = 1/3, find cos 2θ.

Answer: 7/9

cos 2θ = 1 − 2(1/3)² = 1 − 2/9 = 7/9.

Which pair of angles are co-terminal?

Answer: 30° and 390°

390° = 30° + 360°, so 30° and 390° are co-terminal (same position on unit circle).

The graph of y = 2cos(3x) has a period of:

Answer: 120°

Period = 360°/b = 360°/3 = 120°.

If sin A = 0.6 and A is obtuse, then cos A =

Answer: −0.8

cos A = −√(1 − 0.36) = −0.8 (negative because A is in Quadrant II where cosine is negative).

Which is the correct graph transformation of y = sin x to y = sin(x) − 2?

Answer: Vertical shift 2 units downward

Subtracting 2 outside the function shifts the entire graph 2 units downward.

In triangle XYZ, x = 9, y = 12, z = 15. Is this a right-angled triangle, and if so, which angle is 90°?

Answer: Yes, angle Z is 90°

9² + 12² = 81 + 144 = 225 = 15² = z², so the right angle is at Z (opposite the longest side z).