6.3 Graphing Trig Functions Last section we analyzed graphs, now we will graph them. Graph: y = sin θ - 1 First, look at y = sin θ 1 -1 Since the – 1 is on the outside that means we are shifting DOWN ONE unit Graph: y = cos θ + 2 First, look at y = cos θ Since the + 2 is on the outside that means we are shifting UP TWO units 1 -1 Graph: y = 4sin 2θ First, look at y = sin θ Amplitue = 4 Period = 360/2 = 180 Phase Shift = 0° 1 -1 I will change the period first Then change the amplitude Graph: y = -2cos (θ + 90°) First, look at y = cos θ Amplitue = 2 Period = 360/1 = 360 Phase Shift = Left 90° 1 -1 I will change the amplitude first Then change the phase shift Graph: y = 2tan( θ +45) First, look at y = 2tan x Asymptotes are still 90° + 180k° 1 Since 2 in front changes the “amplitude”?? Then each output is doubled -1 We’re not done, go to next slide Graph: y = 2tan( θ +45) Continued 1 -1 Now let’s shift 45° to the right Graph: y = sin ( 2 Θ 270 y 0 90 180 1 0.7 0 + 90°) -0.7 See if you can graph this without graphing each step. 360 450 -1 -0.7 540 630 720 0 0.7 1 Amplitude = 1 Period = 360/½ = 720 Phase Shift = 180° Left (0,1) (4π,1) (π,0) (2π,-1) (3π,0) (5π,0) Graph: y tan 12 x Θ 0 90 y 0 1 180 270 UD -1 360 450 0 1 See if you can graph this without graphing each step. Amplitude = 1 540 630 720 Period = 180/½ = 360 UD -1 0 Phase Shift = 0° Graph: y = 3cos (θ - 90°) FIX THIS!!! First, look at y = cos θ Amplitue = 3 Period = 360/1 = 360° Phase Shift = 90° 1 -1 I will change the period first Then change the amplitude Graph: y = cot (θ – 90°) FIX THIS!!! Cot 0 = Does Not Exist Amplitue = none Period = 180/1 = 180° Phase Shift = 90° Right 1 -1 I will change the period first Then change the amplitude Graph: y = sin x + cos x Best approach - table θ cos θ sin θ sum 0° 1 0 1 45° .71 .71 1.4 90° 0 1 1 135° -.71 .71 0 180° -1 0 -1 225° -.71 -.71 -1.4 270° 0 -1 -1 315° .71 -.71 0 360° 1 0 1 Period = 360 Graph: y = cos 2x – cos x Best approach - table θ cos 2θ cos θ - 0° 1 1 0 45° 0 .71 -.71 90° -1 1 -1 135° 0 -.71 .71 180° 1 -1 2 225° 0 -.71 .71 270° -1 0 -1 315° 0 .71 -.71 360° 1 1 0 Period = ??? Graph: y = tan ( x 2 - 8 ) Amplitude = 1 Period = 180/½ = 360 Phase Shift = π/4 right Graph: y = 2sin x + 3cos x Best approach - table θ 3cos θ 2sin θ sum 0° 0 3 3 45° 1.4 2.1 3.5 90° 2 0 2 135° 1.4 -2.1 -.7 180° 0 -3 -3 225° -1.4 -2.1 -3.5 270° -2 0 -2 315° 2.1 .7 3 3 -1.4 360° 0 Period = 360???