x=(-b+-sq(b^2-4ac)__2a

a^2=b^2+c^2-2bccosA

(sinA)/2=(sinB)/2

sin^2(x)+cos^2(x)=1

lim x->0 (sinx)/x=1

d/dx sinx = cosx

integral of u*dv = u*v - integral of du*v

div F = Px + Qy + Rz