tan^2(30)= 1/cos^2(30) - 1 explain why.
Use the Pythagorean identity sin2(θ)+cos2(θ)=1
sin2(30∘)+cos2(30∘)=1|:cos2(30∘)sin2(30∘)cos2(30∘)+cos2(30∘)cos2(30∘)=1cos2(30∘)sin2(30∘)cos2(30∘)=tan2(30∘)tan2(30∘)+1=1cos2(30∘)|−1tan2(30∘)=1cos2(30∘)−1