* In a right triangle ABC with right angle C,
the tangent of angle A, written tan(A), is leg opposite angle A divided by (/) leg adjacent to angle A;
the sine of angle A, written sin(A), is leg opposite angle A / hypotenuse;
the cosine of angle A, written cos(A), is leg adjacent to angle A / hypotenuse.
Here is an example:
Describe the vector OD above with an ordered pair.
The desired ordered pair contains the coordinates of point D. Let D = (x,y). From the graph you can see that x is positive and y is negative. The absolute values of x and y are OC and CD. Now use trigonometry.
OC/OD = cos(30°)
OC = OD*cos(30°)
OC = 25*cos(30°)
CD/OD = sin(30°)
CD = OD*sin(30°)
CD = 25*sin(30°)
A = (25*cos(30°), -25*sin(30°) = about (21.65, -12.5)
Stumped? Take a look at the answer key![an error occurred while processing this directive]