How do you do sin(135°-30°) - cos(135°)sin(30°)?

xloooveesmilesxxloooveesmilesx
in Science & Mathematics

I tried figuring it out and for the answer I got either 0 or -√2+√2/4

I don't understand how to do this.

Update:

Thanks! I found my mistake and I understand it now. ^___^

Comments

  • tomvtomv

    Depends on what you want to do with it.

    sin(135-30) - cos(135)sin(30) = sin(105) - cos(135)sin(30) = 0.96593 - (-0.70711)(.5) = 0.61237

  • anonymousanonymous

    = sin(135)cos(30) - cos(135)sin(30) -cos(135)sin(30)

    Now, sin(135) = +sin(45)

    cos(135) = -cos(45)

    Therefore

    = sin(45)cos(30) +2cos(45)sin(30)

    = (1/sqrt(2) ) ( sqrt(3) / 2) + 2 (1/sqrt(2) ) (1/2) = [sqrt(6) / 4 ]+ 1/ sqrt(2) = [sqrt(6)+ 2sqrt(2) ] / 4

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