courses › Trigonometry

Sine, cosine, and tangent as side ratios.

Pen and paper is fine · a calculator helps on some problems why?

Learn first (about 3 minutes)

Opens at level 30.

Sign in to start

Builds on: Pythagoras & coordinates (not open yet)

skills · practice stats

From rounds of this course only: box, review and trial answers are left out. Once a skill has 40 tries, it compares your first 20 tries with your last 20.

• Trig ratios par 18 s not tried yet

  worked example

  In a right triangle, the leg opposite angle A is 3, the leg next to angle A is 4, and the hypotenuse is 5. What is tan A? Give a fraction.

  Answer: 3/4

  1. Tangent is opposite ÷ the leg next to A: 3/4.

• Sides from special angles par 18 s not tried yet

  worked example

  A right triangle has hypotenuse 20 and a 30° angle. How long is the leg opposite the 30° angle?

  Answer: 10

  1. sin 30° = 1/2, so the leg opposite the angle is 20 × 1/2 = 10.

• Angle from a ratio par 14 s not tried yet

  worked example

  In a right triangle, sin A = 1/2. What is angle A in degrees?

  Answer: 30

  1. sin 30° = 1/2, so A = 30°.

rest ladder

Win 3 of your last 4 rounds and the course rests. A win is 90% right, within 2× the round's par. Pass the review when it comes back and the next rest is longer.

1. 1 day
2. 3 days
3. 7 days
4. 14 days
5. 30 days
6. 60 days
7. mastered · every 90 days

your rounds

No rounds yet.