: Use the following steps:

Every major problem in spherical astronomy reduces to solving one spherical triangle: the (also called the PZX triangle).

[ \sin(h) = \sin(51.5°)\sin(40°) + \cos(51.5°)\cos(40°)\cos(80°) ]

cos(θ)=sin(ϕ1)sin(ϕ2)+cos(ϕ1)cos(ϕ2)cos(Δλ)cosine open paren theta close paren equals sine open paren phi sub 1 close paren sine open paren phi sub 2 close paren plus cosine open paren phi sub 1 close paren cosine open paren phi sub 2 close paren cosine open paren cap delta lambda close paren (Where is latitude and is the difference in longitude). Multiply