A room is 30 meters long. It's 3 cm long on the drawing. What's the scale of the plan?

A room is 30 meters long. It's 3 cm long on the drawing. What's the scale of the plan?

A room is 30 meters long. It is 3 cm long on the drawing. The scale of the plan is 1:1000

Mathematician's story is in urgent need!

Chen Jingrun doesn't like to play in the park or walk in the street, so he likes to study. When he studies, he often forgets to eat and sleep
One day, when Chen Jingrun was having lunch, he felt his head and said, "Oh, my hair is too long. I should go and have it cut. Otherwise, when people saw him, they thought he was a girl. So he put down his job and went to the barber shop

Know the fabric 65 / kg * 3M, door width 155cm
My understanding of this price is that there are 3 meters in 65 / kg. The price per meter is 21.67. Then the door width is 1.55 meters

The formula of calculating the meter of knitted fabric is related to the gram weight! According to the meter you give, the gram weight is about 200! 1000 / door width / gram weight is equal to the meter. The price of kilogram divided by the meter is equal to the price of each meter

Use 12 matches to make three trapezoids of the same size to form an equilateral triangle

I drew it. I don't know, right

Angle in mathematics is it an axisymmetric figure?
Please express your opinions, talk about your views and explain the reasons. I'm going to watch it tonight

Yes, the axis of symmetry is his bisector

(2008-x) (2006-x) = 2007, find the value of (2008-x) ^ 2 + (2006-x) ^ 2
+(2006-x) ^ 2 square out there

(2008-x)^2+(2006-x)^2
=[(2008-x)-(2006-x)]^2+2(2008-x)(2006-x)
=2^2+2*2007
=4+4014
=4018

If a, B, C and D are the four points of the uncoordinated line on the plane, then what condition does "vector AB and vector CD are collinear" be "(vector) ab × BC = BC × CD = 0"
The answer is that it's not necessary, but if BC is 0, then it's OK

Because we usually do the problem, if it is 2 points on the plane, or several points, it has been the default point is not coincident, so there is no possibility of BC zero vector. Thank you

In the triangle ABC, AB is equal to AC, De is the perpendicular of AB, intersecting AB with D, intersecting AC with E, the circumference of triangle BCE is 15cm, and AC is 8cm
Find the perimeter of triangle ABC as

Let CE = x, CB = y, then AE = be = 8-x
Δ BCE perimeter = be + EC + BC = 8-x + X + y = 15
y=7
Δ ABC perimeter = 8 × 2 + 7 = 23

It is known that the odd function y = f (x) with the domain (- 1,1) is a decreasing function, and f (A-3) + F (8-3a)

Domain-1

High school mathematics problems involving vectors and triangles
It is known that ABC is three fixed points on the plane ∠ ACB = 60 ° moving point P. on the bisector of ∠ ACB, vector CB = vector a, vector CA = vector B │ vector CP │ = m (M > 0). When m is the value, the product of vector CP and (vector BP + vector AP) is the minimum

In fact, the problem is not difficult, the key is in the form of conversion. Vector symbols I will not type out * represents the dot product
CP*（BP+AP)=CP*（CP-a+CP-b)=2CP^2-CP*(a+b)
Because it is an angular bisector, if the parallel line of CB passing through point a intersects at m, then cm = Ca + CB = a + B and is collinear with CP, and the included angle is 0 cos (Cp * cm) = 1
So Cp * (BP + AP) = 2cp ^ 2-CP * (a + b) = 2cp ^ 2-CP * cm = 2 | CP | ^ 2 - | CP | * | cm | let | CP | = x, | cm | = D (constant) 2cp ^ 2-CP * (a + b) = 2X ^ 2-D * x find the minimum value of the quadratic equation of one variable. Finally, CP = (a + b) / 4