c/m rang tong cua ba duong trung tuyen cua mot tam giac lon hon 3/4 chi vi nhung nho hon chu vi cua tam giac do
c/m rang trong tam giac vuong, trung tuyen ung voi canh huyen bang nua canh huyen
c/m rang: neu mot tam giac co trung tuyen thuoc mot canh bang nua canh ay thi tam giac do la tam giac vuong
CMR tong do dai 3 duong trung tuyen cua mot tam giac lon hon 3/4 chu vi va nho hon chu vi cua tam giac ay
chung minh rang neu mot tam giac co 2 duong trung tuyen bang nhau thi tam giac do la tam gac can
do dai ba canh cua tam giac ABC co do dai banh 4;12;x biet x la mot so tu nhien . tim x ( cho biet moi canh cua tam giac nho hon tong hai canh va lon hon hieu cua chung)
cho tam giac ABC can tai A ;duong trung tuyen AM cat duong trung truc cua ACtai K chung minh rang KA=KB=KC
chung minh dinh ly:neu tam giac co mot duong trung tuyen dong thoi la duong trung truc ung voi cung mot canh thi tam giac do la tam giac can
chung minh: trong mot tam giac neu co 3 duong trung tuyen bang nhau thi do la tam giac deu
CHUNG minh dinh li NEU tam giac co mot duong trung tuyen dong thoi la duong trung truc ung voi cung mot canh thi tam giac do la mot tam giac can GIUP NHOA
chung minh neu mot tam giac co duong trung tuyen ung voi mot canh bang nua canh huyen thi tam giac do la tam giac vuong