求救 一條DSE MATHS MC

maxycy

唔多明=="
愛恨交纏 發表於 2-6-2012 23:24

Let angle ABF=y

angle DCF=angle ABE=34

Let AB=CD=AD=BC=x,

tan34=DF/CD
DF=CDtan34=xtan34

AF=AD-DF=x-xtan34

tany=AF/AB=(x-xtan34)/x=(1-tan34)/1=0.325491483...
y=18.02...

So the angle is 18