Question

Evaluate sin(7pi/2)

Answer 1

\[Sin \frac{ 7\pi }{ 2 }\]

Answer 2

subtract 2pi to find it on the unit circle. whenever the value isn't on the unit circle either subtract or add 2pi

Answer 3

hint:

(7pi/2) - 2pi = (7pi/2) - (4pi/2)

(7pi/2) - 2pi = (7pi-4pi)/2

(7pi/2) - 2pi = 3pi/2

that means 7pi/2 and 3pi/2 are coterminal angles which means

sin(7pi/2) = sin(3pi/2)

Answer 4

you just need to evaluate sin(3pi/2)

Answer 5

^basically

Answer 6

so the answer is the sin(7pi/2)?

Answer 7

i meant sin(3pi/2)

Answer 8

you need to keep going and evaluate sin(3pi/2)

Answer 9

i don't know how...

Answer 10

do you have a unit circle with you?

Answer 11

i never learned the unit circle in precalc

Answer 12

i pulled one up on the computer but i don't know how to use it

Answer 13

strange how it's the fundamental basics in trig

let's draw a blank xy axis

Answer 14

draw a circle that is centered at the origin (0,0)

Answer 15

this circle has a radius of 1

that's why it's called the unit circle (unit = 1)

Answer 16

the angle of 3pi/2 radians is equal to 270 degrees

so we start at (1,0) and we rotate 270 degrees counterclockwise to land at (0,-1)