If and is in Quadrant I

MATHEMATICS · Single correct · A Level · Mathematics · Trigonometry · Trigonometry

Problem

If sin⁡θ−cos⁡θ=14\sin\theta-\cos\theta=\dfrac14 and θ\theta is in Quadrant I, then sin⁡θ+cos⁡θ\sin\theta+\cos\theta equals (a) −314-\dfrac{\sqrt{31}}{4} (b) 314\dfrac{\sqrt{31}}{4} (c) 154\dfrac{\sqrt{15}}{4} (d) 318\dfrac{\sqrt{31}}{8}

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