Mathematics for Carpenters and Builders - Carpenter's and Builder's Math, Plans, and Specifications - page 183

90 °

SECOND QUADRANT FIRST QUADRANT

180 ° 0 ° OR 360 °

THIRD QUADRANT FOURTH QUADRANT

270 °

Figure 5-67 The four quadrants of a circle.

in some way. In trigonometry, it is probably less confusing to call
the trigonometric functions simply ratios , which they truly are.
Refer to Figure 5-68 for an explanation of the following. There
are six trigonometric ratios commonly used:

opposite side
hypotenuse

BC
AB

Sine of angle A = or

adjacent side
hypotenuse

AC
AB

Cosine of angle A = or

opposite side
adjacent side

BC
AC

Tangent of angle A = or

adjacent side
opposite side

AC
BC

Cotangent of angle A = or

hypotenuse
adjacent side

AB
AC

Secant of angle A = or

hypotenuse
opposite side

AB
BC

=

Cosecant of angle A or