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amelia1977
16 March 2017
Solution: Cot2x-tan78=1/2(secxsec78) simplifying everything into sine and Cosine. Cos2x/sin2x-sin78/cos78=1/2(secx.1/cos78). Crossing cos78 from right to left and sin2x from the left to the right Then we have cos2xcos78-sin2xsin78=sin2x/2cosx. The right hand can simplify to become cos(2x+78)=sin2x/2cosx recall that sin2x=sin(x+x)=sinxcosx+cosxsinx=2sinxcosx...now applying it here now we have cos(2x+78)=2sinxcosx/2cosx cos(2x+78)=sinx and sinx=cos(90-x) cos(2x+78)=cos(90-x) taking inverse of both sides by multiply it by cos inverse then we have 2x+78=90-x 3x=12 x=4. I would prefer error correction in my solution,if you spotted any.
shenaya
16 March 2017
And to add to the solution,following answers would also suit, 2x+78=270+x => x=192 2x+78 = 450-x => x=124 2x+78=810-x => x=244
shenaya
16 March 2017
Answers are a x=4,12 and 64 degrees according to my solution method
umerhayat
10 April 2017
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