hiiiii

 

we at goIIT answer only one query at one time ..

 

I am also not sure about the (2) question .. i donno wat it means ..

 

well .. for the fisrt one ..

 

 

sin3x + cos4x - 4sin7x = cos10x + sin17x

 

or, sin3x - sin17x - 4sin7x = cos10x - cos4x

 

or, -2sin7x.cos10x - 4sin7x = -2sin3x.sin7x

 

or,  sin7x( cos10x - sin7x + 2) = 0   

 

so, either sin7x = 0 or cos10x - sin7x + 2 = 0

 

if sin7x = 0 .. this means x = 0 , /7 , 2/7 , 3/7 , 4/7 , 5/7 , 6/7 ,  

 

else if cos10x - sin7x + 2 = 0

 

this clearly means that sin7x = 1 and cos10x = -1 which is not possible ..

 

Thus the solution is x = 0 , /7 , 2/7 , 3/7 , 4/7 , 5/7 , 6/7 ,

 

cheers