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Refer to
the right triangle shown in Figure 1, which has sides a, b, and c
that are opposite to the angles A, B, and
C, respectively.
Figure
1. Right Triangle
If
C is the right angle of the triangle (and c is therefore its
hypotenuse), then the following
trigonometric functions may be defined.
Sine
of angle A =
sin A
= a / c
Cosine
of angle A =
cos A = b
/ c
Tangent
of angle A =
tan A = a
/ b
Secant
of angle
A =
sec A = 1
/ cos A = c / b
Cosecant
of angle
A =
csc A = 1
/ sin A = c / a
Cotangent
of angle A =
cot A = 1
/ tan A = b / a
Reminder:
A is the angle opposite to side
a while b
is the side opposite to angle B
and c
is the triangle's hypotenuse
Similarly,
Sine of
angle B = sin B = b / c
Cosine of
angle B = cos B = a / c
Tangent
of angle B = tan B = b / a
Secant of
angle B = sec B = 1 / cos B = c / a
Cosecant
of angle B = csc B = 1 / sin B = c / b
Cotangent
of angle B = cot B = 1 / tan B = a / b
Important Identity:
sin2X
+ cos2X = 1.
Related
Functions:
versine A
=
vers A = 1 - cos A
coversine
A =
covers A = 1 - sin A
haversine
A =
hav A
= (vers A) / 2
hacoversine
A =
hacov A
= (covers A) / 2
exsecant
A =
exsec A
= sec A - 1
Similarly,
versine B
= vers B = 1 - cos B
coversine
B = covers B = 1 - sin B
haversine
B = hav B = (vers B) / 2
hacoversine
B = hacov B = (covers B) / 2
exsecant
B = exsec B = sec B - 1
See Also:
Hyperbolic Functions;
Math Used
in ECE
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