
sin
α
2
5
ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
ðs 2 bÞðs 2 cÞ
bc
r
, where s 5
a 1 b 1 c
2
cos
α
2
5
ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
sðs 2 aÞ
bc
r
tan
α
2
5
ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
ðs 2 bÞðs 2 cÞ
sðs 2 aÞ
r
Area 5
bc sin α
2
Perimeter 5 a 1 b 1 c.
4.5 Degrees or Radians
Angles are measured in degre es or radians: 180
5 π radians; 1 radian 5 180
/π
degrees.
56 Mathematical Formulas for Industrial and Mechanical Engineering