We know that the definitions of the trigonometric
functions are:
sin a = y/r
cos
a = x/r
tan a = y/x
cot a =
x/y
sec a = r/x
csc a =
r/y
We'll calculate r using the Pythagorean theorem in a
right angle triangle:
r^2 = x^2 +
y^2
r = sqrt (x^2 + y^2)
We'll
calculate the values for the trigonometric functions and we'll choose the smallest
positive angle in the standard position for P(3,4).
r =
sqrt (3^2 + 4^2)
r =
sqrt(9+16)
r = sqrt 25
r =
5
sin a = 4/5 ; cos a =
3/5
tan a = sin a/cos a
tan a
= (4/5)/(3/5)
tan a = 4/3
cot
a = 1/tan a
cot a = 3/4
sec a
= 5/3
csc a = 5/4
We'll
calculate the values for the trigonometric functions and we'll choose the smallest
positive angle in the standard position for P(-3,4).
r =
sqrt [(-3)^2 + 4^2]
r =
sqrt(9+16)
r = sqrt 25
r =
5
sin a = 4/5 ; cos a =
-3/5
tan a = sin a/cos a
tan a
= (4/5)/(-3/5)
tan a =
-4/3
cot a = 1/tan a
cot a =
-3/4
sec a = -5/3
csc a =
5/4
We'll calculate the values for the trigonometric
functions and we'll choose the smallest positive angle in the standard position for
P(-1,-3).
r = sqrt [(-1)^2 +
(-3)^2]
r = sqrt(1+9)
r = sqrt
10
sin a = -3/sqrt10
sin a =
-3*sqrt10/10
cos a =
-1/sqrt10
cos a =
-sqrt10/10
tan a =
(-3*sqrt10/10)/( -sqrt10/10)
tan a =
3
cot a = 1/3
sec a =
-sqrt10
csc a = -sqrt10/3
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