help with 3 questions?

(1)

Conversion  from  radians  to  degrees :

radian measure   *   180 /  pi

So

pi  *  180  / pi     =   180°

pi/4  * 180 / pi  =   180 / 4  =  45°

5pi/4  *  180 / pi  =   180 * 5 / 4   =  45 * 5  =  225°

11pi / 6  * 180 /pi  =   11*180 / 6  =  11 * 30  =  330°

5 pi / 3  *  180 / pi   =  5 * 180 / 3  =  5 * 60  =  300°

(2)

Here's an easy  way to  remember  where the trig functions are positive

 First quadrant  :   All

Second quadrant : Sine, Cosecant

Third Quadrant :  Tangent, Cotangent

Fourth Quadrant : Cosine , Secant

Or  :  ASTC  =  "All Students Take Calculus "

So

The tangent is negative in Q4

The cosine is positive in Q1

The cotangent is positve in Q3

(-5, 2√7)   =  (x , y)  = [ - 5, √(4 *7) ]   =  (  -5 , √28   )

r =  √[ x^2 + y^2]

cos B  =  x  / r    =  -5 / √[ (-5)^2 + (√28  )^2 ]  =  -5 / √ [25 + 28]  =  -5 / √ 53

Note that  we can also rationalize  this  as

-5√53

____ =    cos B

  53

OK,  thanks Jenny.....hope all this helped   !!!!