(cos x)^(y)=7x^(2)

lim_(x rarr 0) (cos 9x - cos 7x )/(x^(2)) =

The value of the determinant det[[x+2y,x,x+yx+2y,x,x+yx+y,x+2y,x]]9y^(2)(x+y)3y^(2)(x+y)(d),7x^(2)(x+y)

The factors of (x ^(4) - 7x ^(2) y ^(2) + y ^(4)) are

If tan(7x^(@))=(sin x^(@)cos y^(@)+cos x^(@)sin y^(@))/(cos x^(@)cos y^(@)-sin x^(@)sin^(@)) where x+y=134^(@) ,then the least positive integral value of x, is-

If "cos"^(-1)x+"cos"^(-1)y=(2pi)/(7) , then the value of "sin"^(-1)x+"sin"^(-1)y is

cos x + cos y = (4) / (5), cos x-cos y = (2) / (7) rArr14tan ((xy) / (2)) + 5cot ((x + y) / (2)) =

cos x + cos y = (4) / (5), cos x-cos y = (2) / (7) rArr14tan ((xy) / (2)) + cot ((x + y) / (2)) =

y=a cos x+b sin x+x sin x is a solution of the D.E. A) y_(2)+y=x cos x B) y_(2)+2y=2cos x C) y_(2)+y=2cos x D) y_(2)-y=2cos x

Show that (i) cos x+cos y=2 cos (x+y)/(2) cos (x-y)/(2) (ii) cos x-cos y=-2 sin (x+y)/(2) sin (x-y)/(2) (iii) sin x+sin y=2 sin (dot(x)+y)/(2) cos (x-y)/(2) (iv) sin x-sin y=2 cos (x+y)/(2) sin (x-y)/(2)

(cos x + cos y ) ^(2) + (sin x - sin y ) ^(2) = 4 cos ^(2) ""(x + y )/( 2)