To find the answer to question 8, it is best to have a process of solving the problem

According to the properties of the parallelogram, ad=bc, ad bc, edf= cbf (two straight lines are parallel, the inner wrong angles are equal), def= bcf (two straight lines are parallel, the inner wrong angles are equal), edf cbf(aa), ed:cb=ef:cf (the two triangles are similar, the corresponding sides are proportional);

and e is the midpoint of AD, ed=1 2ad=1 2bc, EF:CF=1:2, it can be seen from the figure that EDF and DCF share the same vertex d, EDF and DCF are equal in height, and the area ratio of EDF to DCF is:

ef:cf=1:2, when the area of def is s, then the area of dcf is 2s

So the answer is: 2s

Hopefully, thank you.

Choose B This question is suitable for special substitution, after all, there is not so much time to calculate multiple choice questions! If it's all big questions, then don't take the exam, always find some easy way!

Passing the point F is fg ad at g, and fh dc is at h

Suppose the parallelogram is a square with an edge length of 2a.

Then the parallelogram DHFG is also square, so FH=FG is in δdef.

s=1/2*de*fg=1/2*a*fg

sδdfc=1/2*dc*fh=1/2*2a*fg=a*fgsδdfc=2sδdef

p (Signal received.)"1")

p (It is indeed the signal "1"|.)Signal received"1") = p(It is indeed the signal "1" that is emitted and the signal is received"1"p (Signal received.)"1" )==

The triangle GDE is similar to the triangle GBA to get GD:GB=1:2

The triangle HAD is similar to the triangle HFB and gives HB:HD=1:2

Equivalent substitution yields hg=bh=gd

Also, your triangle number in question 7 is wrong.

There are 6 in a single triangle; There are 6 triangles made up of two triangles; There are 2 large triangles made up of three triangles; There is 1 large triangle consisting of four triangles, for a total of 15 triangles.

Question 6 is also wrong, table tennis is a sport of two people, and if there are only two people, the playing time of two people is the same, so they play for 3 hours each.

a-10=b-8

a-b = 2a and b are two numbers (a) that are large and should be large (2).