2cos theta=x+(1)/(x),2cos phi=y+(1)/(y)

If 2cos theta=x+(1)/(x) and 2cos phi=y+(1)/(y) then

2cos theta=x+(1)/(x) and 2cos phi=y+(1)/(y) then (A)x^(n)+(1)/(x^(n))=2cos(n theta)n in Z(B)(x)/(y)+(y)/(x)=2cos(theta-phi)(C)xy+(1)/(Xy)=2cos(theta+phi)(D)x^(m)y^(n)+(1)/(x^(m)y^(n))=2(cos m theta+n phi),m,n in Z

If 2 cos theta=x+(1)/(x) and 2 cos phi=y+(1)/(y) then the value of cos (theta+phi) will be

If 2cos A=x+(1)/(x),2cos beta=y+(1)/(y) then show that 2cos(A-B)=(x)/(y)+(y)/(x)

If tan theta* tan phi = sqrt((x-y)/(x+y)) prove that (x - y cos 2theta)(x - y cos 2phi) = x^(2) – y^(2)

If cos theta=(2cos phi-1)/(2-cos phi), then find the value of tan((theta)/(2))

If (x)/(a)cos theta+(y)/(b)sin theta=1 and (x)/(a)sin theta-(y)/(b)cos theta=-1, prove that (x^(2))/(a^(2))+(y^(2))/(b^(2))=2

If (x)/(a)cos theta+(y)/(b)sin theta=1 and (x)/(a)sin theta-(y)/(b)cos theta=1 Prove that :(x^(2))/(a^(2))+(y^(2))/(b^(2))=2