ch4 trig Flashcards
1
Q
definition of an angle in radians
A
theta = arc length/radius
2
Q
degrees to radians
A
- pi/180 degrees
- ans: in reduced fraction not decimal
3
Q
radians to degees
A
180 degrees/pi
4
Q
how many degrees is one radian, explain why
A
- 180 degrees
- bc on circle if half the circumfrence (arc) is πr and u do theta = πr/r , you get just π radians
5
Q
what does theta mean in the equation w/ arc length and radius
A
central angle in radians
6
Q
double angle formulas
A
sin2x = 2sinxcosx
cos2x = cos^2x-sin^2x
7
Q
name the identities
A
- pythagorean
- quotient (tanx)
- reciprocals
- compound angle
- double angles
8
Q
from the compound angle formuals, which one has the same sign nd which is diff?
A
- cos(x+y) has diff sign
- Sin(x+y) has Same Sign
