Unit Circle :
Unit Circle Slide 2:
The Unit Circle is a tool that can be used to find the
values of the trig functions of some of the most common
angles.
The Unit Circle is a circle with a radius of one. It is based
the values of the trig functions of the angles in the special
right triangles. Slide 3:
Note: the angles
can be found
by starting at “0”
and adding
30, 15, 15, 30 –
then repeat. You should
memorize the
3 points in the
1st quadrant. The values at 0, 90, 180 and 270 are
found by remembering that a unit circle has a radius of “1”.
The coordinate of the point at 0 degrees is (1, 0)
since it is over 1 and up 0. The radians follow
a different pattern.
The denominators
beginning at the top and
bottom are 2, 3, 4, 6. All numerators
are pi. Numerator = denominator - 1 Num = denominator + 1 Num = 2den - 1 The other points
can be found
matching the
pts across and
then down. Slide 4:
In order to use the
Unit circle, remember
that the point
represents
(cos x, sin x). Find cos 330.
Find the point at
The first #
in the point is the
cos.
cos 330 = Find sin 180.
Find the point at 180. The second # is the sine.
sin 180 = 0 Slide 5:
Your Turn:
Find the value of the
following. Then click
to check your answers.
Sin 30 =
Cos 315 =
Sin 135 =
Cos 240 =