Page 8 - Dahlia Oktaviani Ginting_4193312002_FlipBook

I a = 2a = I

a
60 =
0
cos
1
2
c
0
tan 30 = a = a = 1 3
b a 3 3
0
tan 60 = b = a 3 = 3
a 0 a
0
c. 0 and 90 angle
To determine the trigonometric ratio of angles 0 and
0
90 use the unit circle in the Cartesian coordinate
0
system.

y

P(x,y)
1 y
 1 x
x
O Q

The point P(x,y) lies on the unit circle. The line OP forms
an angle with the X axis.  dengan sumbu X.
length OQ = unit
x
length PQ = unit and
y
length OP = 1 unit = circle radius.
 OPQ is a right triangle. Trigonometric ratios for angle
 with the X axis.  = x tan  = y
y
=

cos
sin
x
1

;
;
1
If = 0 , then the line OP coincides with the X axis with
0
P I (1 ,0 ) , consequently: I