Convert Radians to Degrees and Vice Versa

A) To convert radians to degrees

Multiply radians by 180 degrees/pi
Example:

3pi/4 ==> degrees

3pi/4 x 180 degrees/pi (pi will cancel out)

540/4 = 135 degrees

B) To convert degrees to radians

Multiply degrees by pi/180 degrees
Example:
60 degrees ==> radians

60 degrees x pi/180 degrees ( degrees will cancel out)

60pi/180 = pi/3

Quadratic Equation: Completing the Square

One way of solving for x in a quadratic equation is by completing the square. Here's how:

x^2 + 6x - 7 = 0 ===> ax^2 +bx + c = 0

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1) Move the constant to the right side. In the equation above, the constant is 7. You can do this by adding the negative value of the constant on both sides of the equation;

x^2 + 6x -7 + (+7) = 0 + (+7)

x^2 + 6x = 7

2) Take half the value of the x-term or b ( 6).

6/2 = 3

3) Square it.

3^2 = 9

4) Add the result to both sides.

x^2 + 6x + 9 = 7 + 9

5) Convert the left side to squared form and simplify the right side.

( x + 3)^2 = 16

6) Take the square root of both sides.

x + 3 = +/- 4

7) Solve for x

x + 3 = 4

x = 4 - 3

x = 1

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x + 3 = -4

x = -4 - 3

x = -7

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Answers:

x = 1 and -7