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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°. ID/Quadratic Quiz. Write all identities Pythagoreans (3) Quotients (2) Cofunctions (6)
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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°
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.
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
COMPARING FUNCTION VALUES OF ACUTE ANGLES Example 1a 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.
COMPARING FUNCTION VALUES OF ACUTE ANGLES Example 1b • 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.
30°- 60°- 90° Triangles Bisect one angle of an equilateral to create two 30°-60°-90° triangles.
30°- 60°- 90° Triangles Use the Pythagorean theorem to solve for x.
FINDING TRIGONOMETRIC FUNCTION VALUES FOR 60° Example 2 Find the six trigonometric function values for a 60° angle.
FINDING TRIGONOMETRIC FUNCTION VALUES FOR 60° (continued) Example 2 Find the six trigonometric function values for a 60° angle.
45°- 45° Right Triangles Use the Pythagorean theorem to solve for r.
45°- 45° Right Triangles adjacent
Function Values of Special Angles sin cos tan cot sec csc 30 45 60