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Paper 4 (9164, Section B) · June 2011 · Projectiles

A particle is projected at an angle θ\theta above the horizontal where θ=sin⁡−1(22)\theta=\sin^{-1}\left(\dfrac{\sqrt{2}}{2}\right). Find θ\theta in degrees.

Model answer

45

Also accepted: 45 degrees, 45,0, 45.0

Explanation

22=12\dfrac{\sqrt{2}}{2}=\dfrac{1}{\sqrt{2}}, and the acute angle whose sine is 12\dfrac{1}{\sqrt{2}} is 45∘45^{\circ}. Its cosine is also 12\dfrac{1}{\sqrt{2}}, so the horizontal and vertical components of the launch velocity are equal.

Derived from ZIMSEC Mathematics 9164/4 Paper 4, June 2011, Q13

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