Bit of a problem with polar coordinates.

[kryptos]

Bit of a problem with polar coordinates. (Only trig knowledge needed.)

Right. So, in this problem, I'm given the polar coordinate point (rad2, 4.39) -- "rad2" being, naturally, short for radical 2. I'm to find the rectangular coordinates of the point, using the formulas:

x = r cos Theta

and y = r sin Theta. In this problem, r = rad2 and Theta = 4.39.

Simple, no? Only for some reason, it's not coming out right with my calculator. I substitute the givens, for:

x = rad2 * (cos 4.39)

and y = rad2 * (sin 4.39).

I have the answers -- they're in the back of the textbook -- but can't figure out the process. x should equal approx. -0.45, and y should equal -1.34. Instead, I find x to equal 1.41 and y to equal 0.11. Am I doing something in the wrong order?

Any help is appreciated. Thanks. ; )

 

[d_leet]

Are you sure your calculator is in radian mode and not degree mode if the 4.39 is inradians?

 

[kryptos]

Actually, no. I hadn't thought of that. But I don't know how to set it in radian mode. Is there some way I could convert the 4.39 into a form usable in degree mode?

 

[d_leet]

Actually, no. I hadn't thought of that. But I don't know how to set it in radian mode. Is there some way I could convert the 4.39 into a form usable in degree mode?

Multiply by 180/pi.

 

[kryptos]

Multiply by 180/pi.

. . . . . . . .

*smacks forehead*

I can't believe I missed that. Thanks so much.