Page 8 - Dhea Anisah Putri_4193111017

°
b. 150 = 150 x = 150 x radians = radians = radians = radians1 ° 150 5 5
180 180 6 6
°
c. −120 = -120 x = -120 x radians = radians = radians1 ° −120 −2
180 180 3
2
= radians−
3

Example 2.

Express the following angles in degrees.

a. radians c. radians
6 6

7
b. 7 radians d. radians
9 9

Answer :

180 °
°
a. radians = x 1 radians = x = 30
6 6 6
°
b. 7 radians = x 1 radians = x = 7 7 180 ° 140
9 9 9
°
30
1
c. radians = x 1 radians = x = 1 1 180 ° ( )
6 6 6
°
°
7
d. radians = x 1 radians = x = = 7 7 180 7 180 ° ( 140 )
9 9 9 9

B. Trigonometry in Right Triangle

Studying trigonometry begins by considering right triangles and acute angles measured
in degrees. An acute angle is an angle that measures more than 0° and less than 90° .

Greek letters are often used to denote angles. Consider a right triangle with one acute

angle. The side opposite the right angle is called the hypotenuse or hypotenuse. The other
side refers to the position relative to the acute angle .One side in front and on the side∝

, , , ,