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Terminal Arm Length and Special Case Triangles. DAY 2. Using Coordinates to Determine Length of the Terminal Arm. There are two methods which can be used: Pythagorean Theorem Distance Formula Tip: “Always Sketch First!” . Using the Theorem of Pythagoras .
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Using Coordinates to Determine Length of the Terminal Arm • There are two methods which can be used: • Pythagorean Theorem • Distance Formula • Tip: “Always Sketch First!”
Using the Theorem of Pythagoras • Given the point (3, 4), draw the terminal arm. 1. Complete the right triangle by joining the terminal point to the x-axis.
Solution 2. Determine the sides of the triangle. Use the Theorem of Pythagoras. • c2= a2 + b2 • c2 = 32 + 42 • c2 = 25 • c = 5
Solution continued 3. Since we are using angles rotated from the origin, we label the sides as being x, y and r for the radius of the circle that the terminal arm would make.
Example: Draw the following angle in standard position given any point (x, y) and determine the value of r.
Using the Distance Formula Thedistance formula: d = √[(x2 – x1)2 + (y2 – y1)2] • Example: Given point P (-2, -6), determine the length of the terminal arm.
Review of SOH CAH TOA • Example: Solve for x. • Example: Solve for x.
Special Case Triangles – Exact Trigonometric Ratios • We can use squares or equilateral triangles to calculate exact trigonometric ratios for 30°, 45° and 60°. • Solution • Draw a square with a diagonal. • A square with a diagonal will have angles of 45°. • All sides are equal. • Let the sides equal 1
45° • By the Pythagorean Theorem, r =
30° and 60° Draw an equilateral triangle with a perpendicular line from the top straight down • All angles are equal in an equilateral triangle (60°) • After drawing the perpendicular line, we know the small angle is 30° • Let each side equal 2 • By the Theorem of Pythagoras, y =
Finding Exact Values • Sketch the special case triangles and label • Sketch the given angle • Find the reference angle
Example: Tan 30° • Example: Tan 30° • Example: Cos 30°
ASSIGNMENT: • Text pg 83 #8; 84 #10, 11, 12, 13