Unit 8
Trigonometry.
Sine, cosine and tangent in a right triangle, the unit circle and radians, and vectors and their components.
Before this unit
The unit, lesson by lesson
Lessons
4 lessons · 23 practice questions · about 2 hours
Sine, cosine and tangent
In a right triangle, the ratio of two sides depends only on the angle. These three ratios are called sine, cosine and tangent.
Finding sides and angles
One angle and one side are enough to work out every other side of a right triangle, and two sides are enough to work out the angle: a ladder, a ramp, a tree, and inverse functions.
The unit circle and radians
Sine and cosine for every angle, above 90 degrees too: the height and width of a point on a circle of radius 1. And radians, the other way to measure angles.
Vectors and their components
A vector is an arrow: a length and a direction. Sine and cosine split it into a horizontal and a vertical component, and with the components you add vectors.