SOLUTION: Good day, can you help me solve this problem? Determine the value of β that will satisfy the ff. sin (5β-10°) = 1/sec(3β+4°) Thank you!

Algebra ->  Trigonometry-basics -> SOLUTION: Good day, can you help me solve this problem? Determine the value of β that will satisfy the ff. sin (5β-10°) = 1/sec(3β+4°) Thank you!      Log On


   



Question 981217: Good day, can you help me solve this problem?
Determine the value of β that will satisfy the ff.
sin (5β-10°) = 1/sec(3β+4°)
Thank you!

Answer by KMST(5328) About Me  (Show Source):
You can put this solution on YOUR website!
sec%28A%29=1%2Fcos%28A%29<--->cos%28A%29=1%2Fsec%28A%29
Applying that,
sin%285beta-10%5Eo%29=1%2Fsec%283beta%2B4%5Eo%29--->sin%285beta-10%5Eo%29=cos%283beta%2B4%5Eo%29
The expressions on both sides of the equal sign must be both positive, or both negative.

If they are both positive,
the angles measuring 5beta-10%5Eo and 3beta%2B4%5Eo
are both in quadrant I.

For two angles between 0%5Eo and 90%5Eo ,
if the sine of an angle and the cosine of the other are the same,
the angles are complementary (their measures add to 90%5Eo ).
In that case, we would have
5beta-10%5Eo%2B3beta%2B4%5Eo=90%5Eo--->8beta-6%5Eo=90%5Eo--->8beta=96%5Eo--->beta=96%5Eo%2F6--->highlight%28beta=12%5Eo%29 .
(That makes 5beta-10%5Eo=50%5Eo and 3beta%2B4%5Eo=40%5Eo ).

However, since coterminal angles have the same trigonometric function values,
there are other solutions with both angles in the first quadrant,
but their measures adding to 90%5E0%2Bk360%5Eo , with k= any integer.
8beta-6%5Eo=90%5Eo%2Bk360%5Eo--->8beta=96%5Eo%2Bk360%5Eo--->beta=%2896%5Eo%2Bk360%5Eo%29%2F8--->beta=96%5Eo%2F8%2Bk360%5Eo%29%2F8--->highlight%28beta=12%5Eo%2Bk45%5Eo%29 for any k integer.
So, 57%5Eo , 102%5Eo , 147%5Eo , 192%5Eo , etc are solutions,
and so are -33%5Eo , -78%5Eo , -123%5Eo , -168%5Eo , etc.

If sin%285beta-10%5Eo%29 and cos%283beta%2B4%5Eo%29 are both negative,
the angles measuring 5beta-10%5Eo and 3beta%2B4%5Eo
are both in quadrant III.
They could be both be between 180%5E0 and 270%5Eo ,
measuring 180%5Eo more than their quadrant I reference angles,
and in that case their measures would add up to
90%5Eo%2B180%5Eo%2B180%5Eo=90%5Eo%2B360%5Eo .
one or both could be coterminal with angles measuring between 180%5E0 and 270%5Eo ,
and in that case their measures would add up to
90%5Eo%2B180%5Eo%2B180%5Eo%2Bp360%5Eo=90%5Eo%2B%28p%2B1%29360%5Eo
In either case, the equation and solution would be the same as above:
8beta-6%5Eo=90%5Eo%2Bk360%5Eo and highlight%28beta=12%5Eo%2Bk45%5Eo%29 for any k integer.