Sum to Product Identities Formula

Equation for calculate sum to product identities is,

sin(θ) + sin(φ) = 2 × sin((θ)+(φ)/2) × cos((θ)-(φ)/2)
sin(θ) - sin(φ) = 2 × cos((θ)+(φ)/2) × sin((θ)-(φ)/2)
cos(θ) + cos(φ) = 2 × cos((θ)+(φ)/2) × cos((θ)-(φ)/2)
cos(θ) - cos(φ) = -2 × sin((θ)+(φ)/2) × sin((θ)-(φ)/2)