'Angle measure': angles give us an insight into the ratio of the length of one line compared to another.
Three common ratios are described below:

Radian measure

The unit circle

The UNIT circle is a circle of radius 1 (see red line from origin to edge of circle). It can be divided into 4 quadrants (labelled Q1-Q4 above). Any point on the circle (p) can be described using Cartesian coordinates (x,y) or polar coordinates (cos, sin).

Polar coordinates are found by creating a right-angled triangle, thenby drawing a perpendicular line from the point p to the x-axis. The angle  is the angle created as shown. Cos  = x/1 = x, and Sin  = y/1 = y, as shown above. 

Thus any point can be represented  by (cos, sinand the sine and cosine of angle  yields a corresponding number. Remember that the sine, cosine and tangent of any angle is just a relationship between two numbers (and so a number).

Solving problems using the unit circle

Solving problems using the unit circle (ii)

LC Solution

Trig formulae questions

L.C. solutions

Trigonometric Graphs

L.C. solution

Sine & Cosine rules

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