Re: Help- trigonometry

On 15 Jan 2006 04:50:06 -0800, hannah_jasmine@xxxxxxxxxxxxx wrote:
>How do you find cos and tan, when you only know sin and whether it is
>acute or obtuse?

Pythagoras.

Draw a triangle with the hypoteneuse = 1, an angle A, and opposite
side, a. then figure the third side from Pythagoras [it will be a
square root relation involving the other two sides.] You can now see
and calculate the other relations from the triangle.

About the obtuse triangle: Draw coordinate axes, and put an A in the
first quadrant, an S in the second, a T in the third, and a C in the
fourth. This gives you the CAST rule, showing which functions are
positive [and so where others will e negative. Look in the second
quadrant (for an obtuse angle) to see which is positive, and so which
will be negative.

With some practice you'll need fewer aids.

.

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