### Author Topic: Can anyone help me do this sin  (Read 3724 times)

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#### There is only one God

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##### Can anyone help me do this sin
« on: February 10, 2013, 10:18:57 AM »
sin90

I heard it is 1 but can anyone confirm please? Thanks

#### Mujahid Saifullah

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##### What?
« Reply #1 on: February 10, 2013, 09:28:08 PM »

#### QuranSearchCom

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• Islam is the Divine Truth!
##### Re: Can anyone help me do this sin
« Reply #2 on: February 10, 2013, 09:33:42 PM »
http://www.scribd.com/doc/36021278/Sin-90-Equals-1-Proof

Ahhh, the old days of Calculus and Differential Equations .  I forgot most of it hehehehhe  .

#### Mujahid Saifullah

• Hero Member
##### Re: Can anyone help me do this sin
« Reply #3 on: February 10, 2013, 09:37:02 PM »
Mathematics is my Achilles' heel, unfortunately.

Quote
"cos(θ)" is the x-component of the (cos(θ),sin(θ)) and so is negative as we move from first quadrant to second quadrant.

However sin(θ) is the y component and does NOT change sign. That is, if 0<θ<90, in the first quadrant, θ+90 is in the second quadrant. sin(θ+90) is still positive as is cos(θ).

Quote
sin(90)=1

You can determine this by looking at the graph y=sin(x), or if you want to determine it geometrically: take a right triangle with hypotenuse of length 1. If you increase the angle theta, the opposite side increases, approaching the length of the hypotenuse (1). When theta reaches 90 degrees, you no longer have a triangle, but sin(90) is still 1.