Please help! The polar coordinates (8, 7π/4) represent the Cartesian point
a. (4, 4)
b. (4√2, 4√2)
c. (-4√2, 4√2)
d. (4√2, -4√2)

Question

Please help! The polar coordinates (8, 7π/4) represent the Cartesian point
a. (4, 4) 	
b. (4√2, 4√2) 	
c. (-4√2, 4√2) 	
d. (4√2, -4√2)

anonymous · Answer

$$
x= \rho \cos(\theta)\
y= \rho \sin(\theta)
$$

anonymous · Answer

Use
$$
\rho= 8\
\theta= 7\pi/4
$$

anonymous · Answer

Notice that
$$7\pi/4 = 2 \pi - \pi/4
$$

anonymous · Answer

Are you there?

anonymous · Answer

i've got x= 8cos(7pi/4) and y=8sin(7pi/4)

anonymous · Answer

How much is the cos and the sin of your angle and you will be done.

anonymous · Answer

$$
\cos(\pi/4) = \sin(\pi/4)= \frac { \sqrt 2}2
$$

anonymous · Answer

It is easy to find your result now.

anonymous · Answer

$$
\cos( 2 \pi -\theta) = \cos(-\theta) =\cos(\theta)
$$

anonymous · Answer

$$
\sin( 2 \pi -\theta) = \sin(-\theta) =-\sin(\theta)
$$

anonymous · Answer

Can you finish it now?