L^2/4=S
L=2sqrt(S)
R=L*cosA=2sqrt(S)*cosA
S=ПR(L+R)=2Пsqrt(s)*cosA*2sqrt(s)(1+cosA)=4sПcosA(1+cosA)
S=144ПcosAcos^2(A/2)
L^2/4=S
L=2sqrt(S)
R=L*cosA=2sqrt(S)*cosA
S=ПR(L+R)=2Пsqrt(s)*cosA*2sqrt(s)(1+cosA)=4sПcosA(1+cosA)
S=144ПcosAcos^2(A/2)