Question

How do you find `(cos5x+cos4x)/(sin3x+sin2x)`, if `14x=3pi`?

How do you solve `(cos5x+cos4x)/(sin3x+sin2x)`, if `14x=3pi`?

Answer 1

`(cos5x+cos4x)/(sin3x+sin2x)`

`=(2cos((9x)/2)cos(x/2))/(2sin((5x)/2)cos(x/2))`

`=(cos((9x)/2))/(sin((5x)/2))`

`=(cos((27pi)/28))/(sin((15pi)/28))`

`=(cos(pi-pi/28))/(sin(pi/2+pi/28)`

`=(-cos(pi/28))/cos(pi/28)=-1`