If `xcosalpha+ysinalpha=xcosbeta+ysinbeta=a,0 lt alpha,beta lt pi/2` then

If xcosalpha+ysinalpha=xcosbeta+ysinbeta=2a then cosalpha cosbeta=

If xcosalpha+ysinalpha=xcosbeta+ysinbeta=2a then cosalpha cosbeta=

If 0 lt alpha lt beta lt (pi)/(2) then

If cos (alpha+beta)=(4)/(5), sin (alpha-beta)=(5)/(13) and 0 lt alpha, beta lt (pi)/(2) then cos 2 alpha=

If cos(alpha+beta)=3/5, sin(alpha-beta)=5/13 , and 0 lt alpha, beta lt pi/4 , then tan(2alpha) is equal to:

cos (alpha+beta)=(3)/(5) and sin (alpha-beta)=(3)/(5) and 0 lt alpha, beta lt (pi)/(2) then sin 2 alpha=

If cos (alpha+beta)=(4)/(5), sin (alpha-beta)=(5)/(13) and 0 lt alpha , beta lt(pi)/(4), then tan 2 alpha=

if xcosalpha+ysinalpha=k=xcosbeta+ysinbeta ,show that x/(cos((alpha+beta)/2))=y/(sin((alpha+beta)/2))=k/(cos((alpha-beta)/2))