Question

find the exact value of sin (-7pi/4)

Answer 1

does pi stand for 3.14

Answer 2

-.0958073086

Answer 3

that should be your awnser

Answer 4

or should i say ite quals to =-0.096 for your estimate awnser

Answer 5

Easier Solution:
sin(7pi/4) =
sin(2pi -- pi/4) =
sin(-pi/4) = -sin(pi/4) =
- sqrt(2)/2

if you dont have to show your work you could also just look at the unit circle and count over 7 pi/4's and see that its below the x axis. sin of pi/4 = 1/sqrt(2) [some people learn sqrt(2)/2, same thing] and being below the x axis makes it negative.

Answer 6

\( - \frac{7 \pi}{4} \) is the same angle if we add \( 2 \pi = \frac{8\pi}{4}\)
\[ - \frac{7 \pi}{4} +\frac{8\pi}{4}= \frac{\pi}{4} \]

so you want \( \sin\left( \frac{\pi}{4} \right) \)
or, in degrees sin(45º)

Answer 7

People memorize the sin, cos and tan of 0º, 30º, 45º, 60º and 90º
see http://2000clicks.com/MathHelp/GeometryTrigCommonAngles.aspx