Techlab 3.7

Back to Chapter 3
This Exploration investigates the symmetry relationships between the trigonometric ratios in the unit circle.

The applet below shows a unit circle similar to the one on page 3-18 of your text.
Instructions
Click the button "Lab 3.4". The red dot represents point "P" on the wheel so that the line joining the dot and the hub (centre) of the wheel makes an angle of 30o with the horizontal. If you press the key "P" on the keyboard of your computer, the point P will rotate counter-clockwise in the positive direction. Pressing "N" will make P move clockwise in the negative direction. The green line on both axes represents the x and y coordinates of the angle that forms P. Answer the questions below.

  1. (a) When P is at 30o, use the green lines to write the coordinates for P as accurately as you can, to two decimal places. Use the unit circle definition and these coordinates to find:
    i. sin30o
    ii. cos30o
    iii. tan30o
    (b) Verify your answers (taking into account measurement accuracy) using a calculator.

  2. (a) Write the coordinates for Q(150o) as accurately as you can, to two decimal places. Use the unit circle definition and these coordinates to find:
    i. sin 150o
    ii. cos 150o
    iii. tan 150o
    (b) Verify your answers (taking into account measurement accuracy) using a calculator.

  3. (a) Write the coordinates for R(210o) as accurately as you can, to two decimal places. Use the unit circle definition and these coordinates to find:
    i. sin 210o
    ii. cos 210o
    iii. tan 210o
    (b) Verify your answers (taking into account measurement accuracy) using a calculator.

  4. (a) Write the coordinates for S(330o) as accurately as you can, to two decimal places. Use the unit circle definition and these coordinates to find:
    i. sin 330o
    ii. cos 330o
    iii. tan 330o
    (b) Verify your answers (taking into account measurement accuracy) using a calculator.

  5. Write a paragraph describing all the patterns and similarities you notice from this investigation. Can you make any conjectures?