TOA CAH SOH
a[square]= b[square] + c[square]
1/2 x base x height , 1/2 ab sin C
a[square] = b[square] + c[square] - 2bc cosA
cosA = ( b[square] + c[square] - a[square] )/ 2bc
sinA/a = sinB/b = sinC/c
a/sinA = b/sinB = c/sinC