AB^2=AC^2+BC^2= 100? AB= 10
CD=AB/2= 10/2=5
1,AB*CE=AC*BC CE=AC*BC/AB=4.8
2.BQ=2t? CP=t? PD=CD-CP=5-t
PD:CD=PF:CE? PF = PD * CE/CD =(5-t)* 4.8/5 = 4.8-0.96t
S(PQB)=BQ*PF/2=4.8t-0.96t^2
y=4.8t-0.96t^2
When t=-b/2a=2.5, y has a maximum value: y=6.
3.? When PQD is an isosceles triangle
QD=BD-BQ=5-2t? (Qpoint is on BD) QD=QP, QP=PD is invalid.
QD=BQ-BD=2t-5 (Q point is on AD)
de^2=cd^2-ce^2= 1.4 df:de = PD:CD df = 0.28(5-t)
QF = QD-DF = 2t-5-0.28(5-t)= 2.28t-6.9? PQ^2=QF^2+PF^2
a,QD=DP,
When QD=BQ-BD=2t-5, 2t-5 = 5t? t= 10/3
When QD=BQ-BD=5-2t, 5-2t=5-t? t=0?
b、QD=PQ sin(CDE)=CE/CD=0.96? QD=PQ ∠QDP=∠QPD=∠CDE
PQ =(PD/2)/sin(CDE)=(5-t)/ 1.92
PQ=QD
(5-t)/ 1.92=2t-5
4.84t= 14.6
t=365/ 12 1
c,DP=PQ? ∠QDP=∠PQD=∠CDE? cos(CDE)=DE/CD=0.28
PQ=(QD/2)/sin(CDE)=(2t-5)/0.28
5-t=(2t-5)/0.28
2.28 tons =6.4
t= 160/57?
Kindergarten mathematics addition and subtraction open class teaching plan;
First,? Design inte