if sinx+siny=1/4, cosx+cosy=1/3 then show that cot (x+y)=7/24
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Given If sinx + siny = 1/4, cosx + cosy = 1/3 then show that cot (x+y) = 7/24
- Given sinx + siny = ¼
- So we have sina + sinb = 2 sin (a + b / 2) cos (a – b / 2)
- cosa + cosb = 2 cos (a + b / 2)cos (a – b / 2)
- Now sinx + siny = ¼
- So 2 sin(x + y / 2) cos (x – y / 2) = ¼ ---------1
- So cosx + cosy = 1/3
- 2 cos (x + y / 2)cos (x – y / 2) = 1/3-------2
- Equation 1 divided by 2 will be
- 2 sin(x + y / 2) cos (x – y / 2) = ¼ /
- 2 cos (x + y / 2)cos (x – y / 2) = 1/3
- tan (x + y / 2) = ¼ x 3/1
- tan(x + y/2) = ¾
- Now we can write tan(x + y) as tan 2 (x + y / 2)
- = 2 tan (x + y / 2) / 1 – tan^2 (x + y / 2)
- = 2(3/4) / 1 – (3/4)^2
- = 3/2 / 16 – 9 / 16
- = 3/2 x 16 / 7
- tan(x + y) = 24 / 7
- Now we have cot (x + y) = 1/ tan(x + y)
- = 1/24/7
- = 7/24
Reference link will be
https://brainly.in/question/7988636
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