Transcript Two more things you should know (that you should have in
Warm up
1. Name the three trig ratios you learned last time.
2. Write the three trig functions as ratios.
3. What is sinA? cosA? tanB?
A 4 m 5 m C 3 m B
Two more things you should know
(that you should have in your notes) Distance formula: D = √(x 2 – x 1 ) 2 + (y 2 – y 1 ) 2
Lengths of the sides of a Δ
When you add the 2 shortest sides, the sum must be GREATER than the longest side, otherwise they won’t connect and you won’t have a Δ.
Using trig ratios in equations
Remember back in 1 st grade when you had to solve: What did you do?
6 72 = x Remember back in 3rd grade when x was in the denominator?
What did you do?
x 12 12 x = 1/2
34 ° x cm 15 cm Ask yourself: In relation to the angle, what pieces do I have?
Opposite and hypotenuse Ask yourself: What trig ratio uses Opposite and Hypotenuse?
SINE Set up the equation and solve: (15)Sin 34 = x 8.39 cm = x 15
12 cm 53 ° x cm Ask yourself: In relation to the angle, what pieces do I have?
Opposite and adjacent Ask yourself: What trig ratio uses Opposite and adjacent?
tangent Set up the equation and solve: (12)tan 53 = x 15.92 cm = x 12
x cm 68 ° 18 cm Ask yourself: In relation to the angle, what pieces do I have?
Adjacent and hypotenuse Ask yourself: What trig ratio uses adjacent and hypotnuse?
cosine Set up the equation and solve: x cos 68 cos 68 X = 18 cos 68 X = 48.05 cm
22 cm 42 cm θ This time, you’re looking for theta. Ask yourself: In relation to the angle, what pieces do I have?
Opposite and hypotenuse Ask yourself: What trig ratio uses opposite and hypotenuse?
sine Set up the equation (remember you’re looking for theta): Sin θ = 22 42 Remember to use the inverse function when you find theta Sin -1 22 = θ 42 31.59
°= θ
You’re still looking for theta. 22 cm θ 17 cm Ask yourself: What trig ratio uses the parts I was given?
tangent Set it up, solve it, tell me what you get. tan θ = 17 22 tan -1 17 = θ 22 37.69
°= θ