
Test solutions with the detailed point scale. Add up your points and spot what to review.
1 Radians and degrees / 3 pts
- \(72\times\dfrac{\pi}{180}=\dfrac{2\pi}{5}\). (1 pt)
- \(\dfrac{5\pi}{12}\times\dfrac{180}{\pi}=75^\circ\). (1 pt)
- \(\dfrac{7\pi}{9}\times\dfrac{180}{\pi}=140^\circ\). (1 pt)
2 Exact values / 4 pts
- Quadrant II, reference angle \(\dfrac{\pi}{3}\), sine positive: \(\dfrac{\sqrt{3}}{2}\). (1 pt)
- Quadrant III, reference angle \(\dfrac{\pi}{6}\), cosine negative: \(-\dfrac{\sqrt{3}}{2}\). (1 pt)
- Quadrant III, reference angle \(\dfrac{\pi}{4}\), tangent positive: \(1\). (1 pt)
- The angle is in quadrant IV with reference angle \(\dfrac{\pi}{6}\), sine negative: \(-\dfrac{1}{2}\). (1 pt)
3 Using the identity / 3 pts
- \(\cos^2\theta=1-\dfrac{64}{289}=\dfrac{225}{289}\), so \(\cos\theta=\pm\dfrac{15}{17}\) (1 pt). Cosine is negative in quadrant III, so \(\cos\theta=-\dfrac{15}{17}\) (1 pt).
- \(\tan\theta=\dfrac{-8/17}{-15/17}=\dfrac{8}{15}\) (1 pt).
4 Reading a sinusoid / 3 pts
- \(4x-\pi=4\left(x-\dfrac{\pi}{4}\right)\), so \(y=2\sin\left(4\left(x-\dfrac{\pi}{4}\right)\right)+3\) (1 pt, with the factoring shown).
- Amplitude 2, period \(\dfrac{2\pi}{4}=\dfrac{\pi}{2}\), phase shift \(\dfrac{\pi}{4}\) to the right, midline \(y=3\) (1 pt for all four values).
- Maximum \(3+2=5\), minimum \(3-2=1\) (1 pt).
5 Equations / 3 pts
- \(\sin x=\dfrac{\sqrt{3}}{2}\), reference angle \(\dfrac{\pi}{3}\), quadrants I and II: \(x=\dfrac{\pi}{3}\) or \(x=\dfrac{2\pi}{3}\). (1 pt)
- Factor: \((2\cos x-1)(\cos x+1)=0\) (1 pt). Then \(\cos x=\dfrac{1}{2}\) gives \(x=\dfrac{\pi}{3},\dfrac{5\pi}{3}\), and \(\cos x=-1\) gives \(x=\pi\) (1 pt for the three solutions).
6 A floating buoy / 4 pts
- Period \(\dfrac{2\pi}{\pi/5}=10\) seconds; maximum \(2+1.5=3.5\) m; minimum \(2-1.5=0.5\) m. (1 pt)
- \(h(2.5)=2+1.5\sin\dfrac{\pi}{2}=3.5\) m. (1 pt)
- \(1.5\sin\dfrac{\pi t}{5}=0\), so \(\dfrac{\pi t}{5}=0,\ \pi,\ 2\pi\) and \(t=0,\ 5,\ 10\) seconds. (1 pt)
- \(3.5\div0.3048\approx11.48\) ft. (1 pt)
Test yourself: quick challenge for Grade 11
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