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 May 25th, 2019, 02:39 PM #1 Member   Joined: Jan 2019 From: tornto Posts: 48 Thanks: 0 Tan inverse 1)- if tanC= -0.6687 find C to the nearest degree C? MY ANSWER -33.77064668 OR SHOULD IT BE -33.80 2)- COS 59 = X/36 X = (COS 59)* (36) = 18.5713707 CORRECT?? 3)- sin 25= 34/x x= (sin 25) * (34) = 14.3690209 correct ??? thanks Last edited by yorkmanz; May 25th, 2019 at 02:52 PM.
May 25th, 2019, 03:15 PM   #2
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Quote:
 Originally Posted by yorkmanz 1)- if tanC= -0.6687 find C to the nearest degree C? MY ANSWER -33.77064668 OR SHOULD IT BE -33.80 2)- COS 59 = X/36 X = (COS 59)* (36) = 18.5713707 CORRECT?? 3)- sin 25= 34/x x= (sin 25) * (34) = 14.3690209 correct ??? thanks
All correct! The first one says to the nearest degree, which would be -34 degrees. (Also note that this is a reference angle. So we would have another solution 180 - 33.77.)

-Dan

May 25th, 2019, 03:32 PM   #3
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Quote:
 Originally Posted by topsquark All correct! The first one says to the nearest degree, which would be -34 degrees. (Also note that this is a reference angle. So we would have another solution 180 - 33.77.) -Dan
Question 1) if tanC= -0.6687 find C to the nearest degree C, C is between 0 and 180 degree?

like that

tanC = - 0.6687

tanC IS NEGATIVE

SO MY ANSWER SHOULD BE BETWEEN 90-180

tan(90+A) = -tanA

tanC = tan(90+A) = -0.6687

tan(90+A) = -tanA

-tanA = -0.6687 remove negatives

A = tan^(-1) 0.6687

A = 33.77

C = 90+33.77 = 123.77 degree CORRECT????

 May 25th, 2019, 03:37 PM #4 Member   Joined: Jan 2019 From: tornto Posts: 48 Thanks: 0 for question 3) 3)- sin 25= 34/x sin5= .423 .423=34/x .423x=34 x=34/.423 x=80.37 correct?
May 25th, 2019, 05:05 PM   #5
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Quote:
 Originally Posted by yorkmanz X = (COS 59)* (36) = 18.5713707 CORRECT?
No. cos(59$^\circ\!$)*36 = 18.5413707 (approximately).

Quote:
 Originally Posted by yorkmanz tan(90+A) = -tanA
That's incorrect. As tan(180$^\circ\!$ - C) = -tan C,
you want 180$^\circ\!$ - 33.77$^\circ\!$... = 146.23$^\circ\!$ approximately (or 146$^\circ\!$ if rounded to the nearest degree).

Quote:
 Originally Posted by yorkmanz 3)- sin 25= 34/x sin5= .423 .423=34/x .423x=34 x=34/.423 x=80.37 correct?
No. You need better accuracy. Also, you typed sin5, but meant sin 25.
sin(25$^\circ\!$) = 0.42261826174...
so x = 34/0.42261826174... = 80.450853827... = 80.45 approximately.

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