330 likes | 421 Views
Warm-Up: January 16, 2014. Given that and find the value of the cos θ. Homework Questions?. Trig Value Table. Memorize it! Quiz 1 st week of 2 nd semester 8 minute time limit All or nothing 20 points There are a lot of patterns
E N D
Warm-Up: January 16, 2014 • Given that and find the value of the cosθ
Trig Value Table • Memorize it! • Quiz 1st week of 2nd semester • 8 minute time limit • All or nothing • 20 points • There are a lot of patterns • We will go over all of the patterns before the quiz
Right Triangle Trigonometry Section 4.3
Right Triangles • A right triangle has a 90˚ angle and two acute angles B c = length of the hypotenuse a = length of side opposite of θ θ A C b = length of side adjacent to θ
Trigonometric Functions SOH-CAH-TOA
Example 1 • Find the value of each of the trigonometric functions of θ. B c 3 θ A C 4
You-Try #1 • Find the value of each of the trigonometric functions of θ. B c 5 θ A C 12
Pythagorean Triples • Pythagorean triples are integer side lengths of a right triangle • 3-4-5 • 5-12-13 • 7-24-25 • 8-15-17 • And many more • And any multiple of any of them (such as 6-8-10)
Assignment • Page 461 #1-19 odd • No calculator
First Few Problems • In Exercises 1-8, use the Pythagorean Theorem to find the length of the missing side of each right triangle. Then, find the value of each of the six trigonometric functions of θ. 5) B B B 3) 26 29 1) 9 10 θ θ θ A A A C C C 12 21
Warm-Up: January 17, 2014 • Find the value of each of the trigonometric functions of θ. B 17 a θ A C 15
Cofunctions • The value of a trig function of an angle is equal to the value of the cofunction of the complement of the angle • If θ is in radians, replace 90˚ with
Example 4 • Find a cofunction with the same value as the given function.
You-Try #4 • Find a cofunction with the same value as the given function.
Trig Functions on TI-83 • All scientific and graphing calculators should have buttons for sin, cos, and tan. • Most do not have csc, sec, and cot. • Make sure that your calculator is set to the correct angle measure (degrees or radians) • TI-83: Press [MODE] and make sure the correct one of “Radian” or “Degree” is highlighted
Angles of Elevation & Depression • The angle formed by a horizontal line and the line of sight to an object that is above the horizontal line is the angle of elevation. • The angle formed by a horizontal line and the line of sight to an object that is below the horizontal line is the angle of depression. angle of depression
Example 5 • Sighting the top of a building, a surveyor measured the angle of elevation to be 24˚. The transit is 5 feet above the ground and 250 feet from the building. Find the building’s height (to the nearest foot).
You-Try #5 • At a certain time of day, the angle of elevation of the sun is 39˚. A tree casts a shadow 37 feet long. Find the tree’s height (to the nearest foot).
Assignment • Page 462 #21-33 odd, 43-49 odd • Calculator required
First Few Problems • In Exercises 21-28, find a cofunction with the same value as the given expression.
Warm-Up: January 27, 2014 • At a certain time of day, the angle of elevation of the sun is 59˚. A tree casts a shadow 24 feet long. Find the tree’s height (to the nearest foot).
Unit Circle Quiz! • Clear everything off of your desk except a pencil and eraser. • 5 minute time limit • All or nothing • Must be turned in by the end of 5 minutes • Do NOT begin until instructed to do so. • Any talking while any quiz is out will result in a zero.
Unit Circle Quiz! • Clear everything off of your desk except a pencil and eraser. • 5 minute time limit
Inverse Trig Functions • If , then • “Theta equals the inverse sine of x” • Other inverse trig functions follow the same format • TI-83: [2nd] [sin]
Example 6 • The Washington Monument is 555 feet high. If you stand ¼ mile away (1320 feet), and look at the top, what is the angle of elevation (to the nearest degree)?
You-Try #6 • A telephone pole is 55 feet tall. A guy wire 80 feet long is attached from the ground to the top of the pole. Find the angle between the wire and the pole to the nearest degree.
Assignment • Page 462 #35-42 ALL
Assignment Problems • In Exercises 35-38, use a calculator to find the value of the acute angle θ to the nearest degree. • In Exercises 39-42, use a calculator to find the value of the acute angle θ in radians, rounded to three decimal places.