Middle school math problems ask for help thanks

ab=4 3bc=ac bc=36cm ab=ac=48cmap=12cm The velocity of the ball is 2cm s2After 18 seconds, Q and R moved on the same side for the first time, and they moved on the same side for 6 seconds.

x = 9 after 9 sec cr = cq

Let ab=ac=x and bc=y. 1/4x=1/3y ；2x+y=132 ；y=132-2x ；

1/4x=1/3(132-2x)=44-2/3x ；1/4x+2/3x=44 ；11/12x=44 ；x=48cm ；y=132-2*48=36cm ；

It is known that BC is 36cm long, 1 3*36 6=12 6=2cm s;

The velocity of the three balls is known to be the same, because BC is the shortest distance, so Q will reach point C first and then move on AC with R.

The velocity of the ball is known to be 2 cm s, and when r moves to point a, it is not in line with q.

3 It is known that the ball velocity is the same as 2cm s, and when cr=cq, bq=cr=cq; Then bc=bq+cq.

bc=36cm ；bq=36/2=18cm ；So 18 2=9s when cr=cq

The arc length is equal to (120 search 360)2 r=(1 3)2*3 =2, and the circumference of the conical bottom circle is equal to the arc length of the fan.

The radius of the circle on the bottom surface of the cone is r=c (2 )=2 2 =1cm

First calculate the arc length of the peace negotiation beam fan to call the shape of the movement.

Arc length = n r 180 = 120 3 180 = 2 cm The circumference of the bottom surface of the cone = the arc length of the fan = 2 cm

The radius of the bottom surface of the servant is r cm

2πr=2π

r=1﹙cm﹚

1) Not necessarily congruent, in the triangle ABC, take AD as the axis of symmetry as the symmetry line of AC (think of AD as a mirror), and intersect BC at the point C'posture, take a for a'Take b as b', then the triangle Changwu abc and a'Resistant to book solution B'c'Eligible but not all.

2) 20 degrees.

1.Proof: In the triangle ABC with the three envy open cons angle A'b'c'

ab=a'b'"Known".

Because {ac=a'c'"Known".

ad=a'Fraternity D'Morning shed "Known".

So triangle ABC is all equal to triangle A'b'c'

Question 2: I don't know if I don't have a picture.

With the Jia Xian Triangle.

Jia Xian triangle description: This is the coefficient table of the power of the binomial, that is, the coefficient situation of n times of a + b is found in the n+1 line of the triangle.

Method: (a+b) 2=a 2]+2ab+b 2(a+b) 5=a 5+5a 4b+10a 3b 2+10a 2b 3+5ab 4

And so on ......, which can solve many problems of binomial higher power] Therefore, (x-2) 4=x 4+

4x^3×（-2）+6x^2×(-2)^2+4x×(-2)^3+(-2)^4

x 4-8x 3+24x 2-32x+16. a=1b=-8c=24

d=-32e=16

So, a+b+c+d+e=1

a+c+e=-7

Such as the line of reputation to check the file of the illusory return map.

I lazily wrote it with Zen and gave me the general idea.

1) Prove EHO and DGC congruence.

eh=dg eo=dc heo= gdc (the last two are equal and come out with a parallel line).

Then you can get oh=cg

OHE= CGD, subtract the spring by 180° to get OHG= CGH, and get OH parallel CG

So OH and CG are parallel and equal, so OHCG is a parallelogram.

This kind of proof topic is annoying to write proof that trembling dust, but in fact, the idea is quite simple.

2) Yes, the dg remains the same.

Because it is a perpendicular line that C leads to both sides, the OECD is a rectangle that is constantly established.

oc is the radius of this thing, which is also the diagonal of the rectangle.

oc=de=3 is certain, so dg=1 3de=1 should be, that's right, welcome to correct.

Attack damage is x, accuracy is y

After n shots, xn=10000-n, yn=1+damage after n shotszn=xn yn=(10000-n)(1+This is a quadratic function, reaching a maximum when n=499 (2, the maximum is 1255005.)

When n=10000, zn=0 means that the total number of total damage is sn=z0+z1+z2+.z9999==8383338250

Solution: Set the attack power to x and the accuracy to y

After n shots, x=10000-n, y=1+ after 10,000 shots, the base attack damage is 0 and no damage is gone.

damage = xy = (10000-n) (1 + when n = 888, take the maximum value as the final loss of HP = 10000*1+ 9999* +9998* (10000-n+1)*[1+

Nth shot:

Max damage = (10000-n+1) * [1+.]

Final HP lost = 10000*1+ 9999* +9998* (10000-n+1)*[1+

Now junior high school children, I can't afford to hurt them.