Trigonometry Section 4.2

1. Trigonometry Section 4.2 Trigonometric Functions: The Unit Circle

2. Definitions of Trig Functions on Unit Circle • Sin t • Cos t • Tan t • Csc t • Sec t • Cot t • These are only true when r=1; we will generalize to any radius r in section 4.4.

3. ASTC on Unit Circle • ASTC is an acronym that stands for _____________________. • A means that all of the basic trigonometric functions are positive in quadrant _____. • S means that only the sine and the _____ are positive in quadrant _____. • T means that only the tangent and the _____ are positive in quadrant _____. • C means that only the cosine and the _____ are positive in quadrant _____.

4. Periodic, Even, Odd Functions • A function is periodic is it repeats for a length c. This length c is called the period. • The basic trigonometric functions are _____. • An even function has _____ symmetry. • An odd function has _____ symmetry. • Cosine is an _____ function. • Sine and tangent are _____ functions.

5. Evaluate the Trig Functions • Ex 1 • If the sin (t)=3/5, what is the sin(-t)=? • If the cos (t)=3/5, what is the cos(-t)=? • If the tan(-t)= -10, what is the tan(t)=?

6. CAUTION • When working out problems, check whether your calculator is in radian or degree mode!!!

7. Homework • 1-52