If `cos alpha=4/5 and cos beta =5/13,` prove that `cos (alpha-beta)/2=8/sqrt 65.`

If cosalpha=3/5 and cosbeta=5/13 then cos^2((alpha+beta)/2)=16/65

If cos alpha=(3)/(5) and cos beta=(5)/(13), then cos^(2)backslash(alpha-beta)/(2)=

If sin alpha+sin beta=a and cos alpha+cos beta=b prove that :cos(alpha-beta)=(1)/(2)(a^(2)+b^(2)-2)

if cos alpha=(3)/(5) and cos beta=(4)/(5) find the value of cos((alpha-beta)/(2))

If coa alpha+cos beta=(1)/(3) and sin alpha+sin beta prove that cos((alpha-beta)/(2))=+-(5)/(24)

If s in alpha+s in beta=a and cos alpha+cos beta=b prove that: cos(alpha-beta=(a^(2)+b^(2)-2)/(2))

If sin alpha=(3)/(5) and cos beta=(9)/(41) find the value of sin(alpha-beta) and cos(alpha+beta)

If cos alpha+cos beta=(1)/(3) and sin alpha+sin beta=(1)/(4) prove that cos[(alpha-beta)/(2)]=+-((5)/(24))

If cos alpha+cos beta=0=sin alpha+sin beta, then prove that cos2 alpha+cos2 beta=-2cos(alpha+beta)

If cos alpha+cos beta=0=sin alpha+sin beta, then prove that cos2 alpha+cos2 beta=-2cos(alpha+beta)