+0  
 
0
78
4
avatar+1690 

Hi! I need some help with these 2 questions. thank you in advance.

 

 

2.

 Feb 13, 2020
 #1
avatar+109740 
+2

First one

 

Is not one-to-one

(-pi/2, pi/2)

 

 

Second one....Correct  !!!

 

 

cool cool cool

 Feb 13, 2020
 #2
avatar+1690 
0

 

im very confused on how to solve for this one, could you check it out as well?

jjennylove  Feb 13, 2020
 #3
avatar+1690 
0

they were correct, thank you!

jjennylove  Feb 13, 2020
 #4
avatar+109740 
+2

cos  ( arcsin (-0.845))

 

Easy way : 

 

arcsin (-0.845) = - 57.67°

 

cos (-57.67°)  ≈ .535 

 

"Expert" way

 

We are looking for  the cosine  of an angle whose sine =  -845/ 1000 =  y  /r

 

Remember that cosine  =  x /r

 

We need  to  find x  

 

x =  ±√ [ r^2 - y^2]  = ±√ [ 1000^2 - 845^2 ] = ±534.76 = ±535

 

This angle is in the 4th quadrant  (the sine is negative there).....but  the cosine is positive in this quadrant

 

So

 

cosine  for this angle =  x / r  =  535 / 1000   =  .535

 

 

cool  cool cool 

 Feb 13, 2020

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