Right Triangles and Trigonometry

SAT Math· difficulty 4/5

If sinθ+cosθ=75\sin\theta + \cos\theta = \frac{7}{5}, what is sinθcosθ\sin\theta\cos\theta?

  • A

    2425\frac{24}{25}

  • B

    725\frac{7}{25}

  • C

    4950\frac{49}{50}

  • D

    1225\frac{12}{25}

    check_circle

Explanation

(sinθ+cosθ)2=1+2sinθcosθ=4925(\sin\theta+\cos\theta)^2=1+2\sin\theta\cos\theta=\frac{49}{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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