Example 1:

Find the six trigonometric ratios of the angle theta in the following diagram:

Solution:
sinO = __opposite
sintheta = . ____________
sin0 = __hypotenuse

sin.. =__2/3
csc0 = __hypotenuse
csctheta = . ____________
csc0 = __opposite

csc.. =__3/2
cos0 = __adjacent
costheta = . ____________
cos0 = __hypotenuse

cos.. =__SQRT(5)/3
sec0 = __hypotenuse
sectheta = . ____________
sec0 = __adjacent

sec.. =__3/SQRT(5)
tanO = __opposite
tantheta = . ____________
tan0 = __adjacent

tan.. =__2/SQRT(5)
cot0 = __adjacent
cottheta = . ____________
cot0 = __opposite

csc.. =__SQRT(5)/2



Example 2:

If cosalpha = 3/4, find the other five trigonometric ratios of alpha.

Solution:
Since cosalpha is defined as the ratio of the adjacent side to the hypotenuse, we drow a triangle with hypotenuse of length 4 and a side of length 3 adjacent to alpha. We use the Pythagorean Theorem to find the opposite side. Let it be x for now. Then we get:
    32 + x2 = 42
    Therefore:
    x2 = 7 so x = SQRT(7)

Hence the triangle looks like:

________

So the other trig ratios are as follows:

sinalpha = SQRT(7)/4 cscalpha = 4/SQRT(7)
secalpha = 4/3
tanalpha = SQRT(7)/3 cotalpha = 3/SQRT(7)

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