Reference Triangle
Please be patient while the Java applet loads.
Directions: Move slider θ in lower lefthand corner to move point P around the circle.
Did you notice:
The opposite side of right trianlge is always vertical (like yaxis).
The adjacent side of right trianlge is always horizontal (like xaxis).
The hypotenuse is the radius of the circle.
If the radius (hypotenuse) is 1, did you notice:
sin θ = y
cos θ = x
tan θ is slope (y/x or sin θ/cos θ)
Did you notice angle θ was restricted mostly to 0°, 30°, 45°, 60°, and 90°?
Find sin 90° and sin 270°. What is their relationship to yaxis?
Find cos 0° and cos 180°. What is their relationship to xaxis?
Find sin 0° and sin 180°. What is their relationship to xaxis?
Find cos 90° and cos 270°. What is their relationship to yaxis?
Find tan 90° and tan 270°. Why is it "?" or undefined?
Find tan 0° and tan 180°. Why is it zero?
What do you know about slopes of vertical and horzontal lines?
What do you know about tangent when vertical or horzontal?
