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how to solve cos70/sin20+cos57cosec33-2cos60?

  • maths -

    Did you notice that in the first two terms the angles mentioned are complimentary angles?
    And did you know that cos 70 = sin 20 ?

    so....
    cos70/sin20+cos57cosec33-2cos60
    = cos70/sin20 + cos57/sin33 - 2cos60
    = sin20/sin20 + cos57/cos57 - 2cos60
    = 1+1 - 2(1/2)
    = 1

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