1. WARM-UP Write each function in terms of its cofunction. (a) cos 48°
= sin (90° – 48°) = sin 42°
(b) tan 67°
= cot (90° – 67°) = cot 23°
(c) sec 44°
= csc (90° – 44°) = csc 46°

2. ID/Quadratic Quiz Write all identities Pythagoreans (3) Quotients (2)
Cofunctions (6)
Reciprocal (6)
Solve the quadratics
5. x2 + 11x + 24 = 0
6. (x – 3)2 – 4 = 0
7. Write the quadratic formula.

3. Trig Game Plan Date: 9/24/13 2.1b Trig Functions of Acute Angles
Section/Topic
2.1b Trig Functions of Acute Angles
Objective (Trig Standard 9a)
Students will be able to apply trig concepts to right triangles using right-triangle-based definitions and cofunctions ID’s.
Homework (with announcements)
p68 (23 to 42, 59 to 64)
Late start tomorrow

4. Increasing/Decreasing Functions
As A increases, y increases and x decreases.
Since r is fixed,
sin A increases
csc A decreases
cos A decreases
sec A increases
tan A increases
cot A decreases

5. Determine whether each statement is true or false.
Example 1a
COMPARING FUNCTION VALUES OF ACUTE ANGLES
Determine whether each statement is true or false.
(a) sin 21° > sin 18° (b) cos 49° ≤ cos 56°
(a) In the interval from 0 to 90, as the angle increases, so does the sine of the angle, which makes sin 21° > sin 18° a true statement.
(b) In the interval from 0 to 90, as the angle increases, the cosine of the angle decreases, which makes cos 49° ≤ cos 56° a false statement.

6. Determine whether each statement is true or false.
Example 1b
COMPARING FUNCTION VALUES OF ACUTE ANGLES
Determine whether each statement is true or false.
(a) tan 25° < tan 23°
In the interval from 0° to 90°, as the angle increases, the tangent of the angle increases.
tan 25° < tan 23° is false.
(b) csc 44° < csc 40°
In the interval from 0° to 90°, as the angle increases, the sine of the angle increases, so the cosecant of the angle decreases.
csc 44° < csc 40° is true.

7. 30°- 60°- 90° Triangles
Bisect one angle of an equilateral to create two 30°-60°-90° triangles.

8. 30°- 60°- 90° Triangles
Use the Pythagorean theorem to solve for x.

9. Find the six trigonometric function values for a 60° angle.
Example 2
FINDING TRIGONOMETRIC FUNCTION VALUES FOR 60°
Find the six trigonometric function values for a 60° angle.

10. Find the six trigonometric function values for a 60° angle.
Example 2
FINDING TRIGONOMETRIC FUNCTION VALUES FOR 60° (continued)
Find the six trigonometric function values for a 60° angle.

11. 45°- 45° Right Triangles
Use the Pythagorean theorem to solve for r.

12. 45°- 45° Right Triangles
adjacent

13. 45°- 45° Right Triangles

14. Function Values of Special Angles
sin 
cos 
tan 
cot 
sec 
csc 
30
45
60