the swimming pool didn't open until 10.45 a.m. yesterday .

It was .................

there were about 90 to 100 people at the concert last night 

x²-4x+3/-5x-20<0

trong mat phang toa do Oxy ,cho hinh chu nhat ABCD co phuong trinh duong thang AB:x-2y+1=0 va duong cheo BD:x-7y+14=0

a)tim toa do diem B.

b) viet phuong trinh tong quat cua duong thang BC.

c)viet phuong trinh duong tron tamBco ban kinh BIbietI(-1/5;-3/5)

cho goc α thoa man π/2<α<π va sin α=1/3.tinh cos α

rut gon bieu thuc F=cosx.tan x/sin²x-cotx .cosx