N
naughtygirl5493


cho hinh chop S.ABCD, day la hinh thang ( BC//AD), BC=2a, AD=a, AB=b, mat ben SAD la tam giac deu. (a) la mat phang qua M tren canh AB va song song voi SA va BC, (a) cat CD, SC, SB lan luot tai N, P, Q.
a, c/m: MNPQ la hinh thang can
b, tinh dien tich thiet dien cua hinh chop theo a, b, AD=x ( 0<x<b)
tinh gia tri lon nhat cua thiet dien do.
a, c/m: MNPQ la hinh thang can
b, tinh dien tich thiet dien cua hinh chop theo a, b, AD=x ( 0<x<b)
tinh gia tri lon nhat cua thiet dien do.