trigonometry Flashcards
1
Q
what is a radian
A
a radian is a unit measurement of angles equal to about 57.3 degrees, equivalent to the angle subtended at the centre of a circle by an arc equal in length to the radius
2
Q
how to know it is in radians (not degrees)
A
angle (θ) is given in terms of π or it has floating c (not the °)
3
Q
how many radians in a circle
A
2π
4
Q
area of triangle
A
1/2abSinC
5
Q
area of sector (degrees)
A
angle/360 X π X r²
6
Q
area of sector (radians)
A
0.5 X θ X r²
7
Q
arc length (degrees)
A
angle/360 X 2π X r
8
Q
arc length (radian)
A
θ X r
9
Q
π radians =
A
180°
