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D.EDWARDS. TRIGONOMETRY. Pythagoras’ theorem. Square on Hypotenuse. =. +. Square on Leg 1. Square on Leg 2. Sine Cosine Tangent. Trigonometric functions. Prove:. Trigonometric identities. Special Angles. Trigonometric functions. proof. proof. proof. ?. ?. ?. ?. ?. ?. ?. ?.
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D.EDWARDS TRIGONOMETRY
DEdwards Pythagoras’ theorem Square on Hypotenuse = + Square on Leg 1 Square on Leg 2
Sine • Cosine • Tangent Trigonometric functions
Prove: • . • . Trigonometric identities
Special Angles DEdwards Trigonometric functions proof proof proof ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
Sin 30° = • Cos 30° = • Tan 30° = • Sin 60° = • Cos 60° = • Tan 60° = Trigonometric functions 60° 30° 2 2 60° 60° 1 2 table
Sin 45° = • Cos 45° = • Tan 45° = Trigonometric functions 45° 1 1 table
Trigonometric Graphs are PERIODIC i.e. they repeat themselves after a “cycle” is complete GRAPHS OF TRIGONOMETRIC FUNCTIONS
GRAPHS OF TRIGONOMETRIC FUNCTIONS y-intercept = 0 x-intercepts = 0 °, ±180°, ±360°
GRAPHS OF TRIGONOMETRIC FUNCTIONS y-intercept = 1 x-intercepts = ±90°, ±270°
Complementary Relationships • Sin x = Cos ( 90 - x) • Cos x = Sin ( 90 - x) • Tan x = Trigonometric relationships
Supplementary Relationships • Sin x = Sin ( 180 - x) • Cos x = - Cos ( 180 - x) • Tan x = - Tan ( 180 - x) Trigonometric relationships
GRAPHS OF TRIGONOMETRIC FUNCTIONS The function has ASYMPTOTES at these points
TRIGONOMETRIC FUNCTIONS on the cartesian plane (0,1) THE UNIT CIRCLE Circle on the Cartesian plane with radius of 1 unit
TRIGONOMETRIC FUNCTIONS on the cartesian plane (0,1) THE UNIT CIRCLE Terminal Side: Other side forming desired angle Initial Side: Positive side of x axis
TRIGONOMETRIC FUNCTIONS on the cartesian plane (0,1) THE UNIT CIRCLE: 1st Quadrant Terminal Side Theta θ: Angle between Terminal side & Initial side Reference Angle α: Acute Angle between Terminal Side & x-axis Initial Side
TRIGONOMETRIC FUNCTIONS on the cartesian plane (0,1) THE UNIT CIRCLE: 2nd Quadrant Terminal Side Theta , θ Reference Angle α Initial Side
TRIGONOMETRIC FUNCTIONS on the cartesian plane (0,1) THE UNIT CIRCLE: 3rd Quadrant Theta , θ Reference Angle α Initial Side Terminal Side
TRIGONOMETRIC FUNCTIONS on the cartesian plane (0,1) THE UNIT CIRCLE: 4th Quadrant Theta , θ Reference Angle α Initial Side Terminal Side
TRIGONOMETRIC FUNCTIONS on the cartesian plane (0,1) THE UNIT CIRCLE Coordinates of points on the unit circle show (cosθ , sin θ) When the terminal side is drawn through that point
TRIGONOMETRIC FUNCTIONS on the cartesian plane (0,1) THE UNIT CIRCLE (cosθ , sin θ) P(a , b) x <- 1 (radius) -> <- b -> O θ ° X <- a ->
TRIGONOMETRIC FUNCTIONS on the cartesian plane (0,1) THE UNIT CIRCLE Terminal Side Coordinates of points on the unit circle show (cosθ , sin θ) When the terminal side is drawn through that point x θ=90 ° cos90 °=0 sin90 ° =1 Hence point on circle is (0,1)
TRIGONOMETRIC FUNCTIONS on the cartesian plane (0,1) THE UNIT CIRCLE Coordinates of points on the unit circle show (cosθ , sin θ) When the terminal side is drawn through that point θ=180 ° Cos180° = -1 Sin 180° = 0 Hence point on circle is(-1,0) x Terminal Side
DEdwards TRIGONOMETRIC FUNCTIONS on the cartesian plane (0,1) THE UNIT CIRCLE Coordinates of points on the unit circle show (cosθ , sin θ) When the terminal side is drawn through that point θ=270 ° Cos 270° = 0 Sin 270° = -1 Hence point on circle is (0, -1) x Terminal Side
TRIGONOMETRIC FUNCTIONS on the cartesian plane (0,1) θ=30 ° Cos 30 °= 0.866=0.9(1dp) sin30 ° = 0.5 Hence point on circle is (0.9 , 0.5) THE UNIT CIRCLE (cosθ , sin θ) (0.9 , 0.5) x θ=30 °
TRIGONOMETRIC FUNCTIONS on the cartesian plane (0,1) A ll are Positive THE 1st QUADRANT 0 <θ≤ 90 For all points (x,y) x is positive & y is positive So, all points (cos θ,sin θ ) Cos θ :positive Sin θ : positive Tan θ = sin θ /cos θ=positive
TRIGONOMETRIC FUNCTIONS on the cartesian plane S (0,1) A INE (only) is Positive ll are Positive THE 2nd QUADRANT 90 ° <θ≤ 180° For all points (x,y) x is negative & y is positive So, all points (cos θ,sin θ ) Cos θ :negative Sin θ : positive Tan θ = sin θ /cos θ=negative
TRIGONOMETRIC FUNCTIONS on the cartesian plane S (0,1) A INE (only) is Positive ll are Positive THE 3rd QUADRANT 180 ° <θ≤ 270° For all points (x,y) x is negative & y is negative So, all points (cos θ,sin θ ) Cos θ :negative Sin θ : negative Tan θ = sin θ /cos θ=positive T AN (only) is Positive
TRIGONOMETRIC FUNCTIONS on the cartesian plane S (0,1) A INE (only) is Positive ll are Positive THE 4th QUADRANT 270 ° <θ≤ 360° For all points (x,y) x is positive & y is negative So, all points (cos θ,sin θ ) Cos θ :positive Sin θ : negative Tan θ = sin θ /cos θ=negative C T OS (only) is Positive AN (only) is Positive
TRIGONOMETRIC FUNCTIONS on the cartesian plane S (0,1) A INE (only) is Positive ll are Positive C T OS (only) is Positive AN (only) is Positive
“CAST” Relationships • Sin x = Sin (180 - x) = -Sin (180 + x) = Sin ( 360 - x) • Cos x = -Cos (180 - x) = -Cos (180+ x) = Cos (360 - x) • Tan x = -Tan (180 - x) = Tan (180+ x) = -Tan(360 - x) Trigonometric relationships