Right Triangles and Trigonometry

SAT Math· difficulty 4/5

If sinθcosθ=15\sin\theta-\cos\theta=\frac{1}{5}, what is sinθcosθ\sin\theta\cos\theta?

  • A

    2425\frac{24}{25}

  • B

    1325\frac{13}{25}

  • C

    125\frac{1}{25}

  • D

    1225\frac{12}{25}

    check_circle

Explanation

(sinθcosθ)2=12sinθcosθ=125(\sin\theta-\cos\theta)^2=1-2\sin\theta\cos\theta=\frac{1}{25}, so 2sinθcosθ=24252\sin\theta\cos\theta=\frac{24}{25} and sinθcosθ=1225\sin\theta\cos\theta=\frac{12}{25}.

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