11-1

So, chapter 11 was pretty easy chapter *thumbs up*. Today I'm going to teach section 1 of the chapter. That is polar and rectangular coordinates. I will teach how to convert from polar to rectangular and vice versa. Rectangular coordinates are in the form of (x,y), while polar coordinates are in the form of (r,theta). In order to do the convserions, you need the following formulas.

polar to rectangular : x= rcos(theta) y= rsin(theta)

rectangular to polar : r= square root of x^2+y^2 theta= tan^-1(y/x)

Here comes the examples!

Example 1 : Give the polar coordinates for (0,12)

r= square root of 0^2+12^

r= +/-12

theta = tan^-1(12/0)

theta = 90 degrees, 270 degrees

(12, 90 degrees), (-12,270 degrees)

Example 2 : Give the rectangular coordinates for (-3, 90 degrees)

x= -3cos(90 degrees)

x= -3(0)

x= 0

y= -3sin(90 degrees)

y= -3(1)

y= -3

(0,-3)