Several mathematical geometry proof questions! In a known parallelogram, extend Da to F, make AF = AC, connect CF with ab at point E, angle ABC = 120 degrees, angle CEB = 45 degrees, BC = 2, and find the length of BD (which cannot be proved by similar triangle) It is known that in the quadrilateral ABCD, ad = BC, F and m are the midpoint of DC and ab respectively, the extension lines of AD and MF intersect at g, and the extension lines of MF and BC intersect at E It is known that in the triangle ABC, e is the midpoint of BC, ad is perpendicular to BC, the perpendicular foot is D, de = 1 / 2Ab Magic snow baby 22:50:10

Several mathematical geometry proof questions! In a known parallelogram, extend Da to F, make AF = AC, connect CF with ab at point E, angle ABC = 120 degrees, angle CEB = 45 degrees, BC = 2, and find the length of BD (which cannot be proved by similar triangle) It is known that in the quadrilateral ABCD, ad = BC, F and m are the midpoint of DC and ab respectively, the extension lines of AD and MF intersect at g, and the extension lines of MF and BC intersect at E It is known that in the triangle ABC, e is the midpoint of BC, ad is perpendicular to BC, the perpendicular foot is D, de = 1 / 2Ab Magic snow baby 22:50:10

1. Make cm ⊥ AB at m through point C, and find out ∠ FCB = 15 °, ∠ ECM = 45 °, ≠ BCM = 30 °, ∫ BC = 2, ∫ BM = 1, CM = √ 3. ∫ ad ∥ BC, ∫ f = ∠ FCB = 15 °, ∫ AF = AC ∫ f = ∠ ACF = 15 ∫ ACM = 60 ∫ cam = 30 °, ∫ am = 3, ab = 2. ∫ bad = 60 ° and ∫ BD = AB = 2

1. The figure is made up of ()
2. Point move into (), () move into surface, surface move into ()
3. The nib quickly slides on the paper and writes out one English letter after another, which explains (); when the wheel rotates, it looks like a whole round surface, which explains (); a right triangle rotates around its right side to form a cone, and explains ()
4. The side and bottom of the cylinder intersect into () lines, which are () lines

1. A figure is made up of (points, lines, faces)
2. A point moves into a line, a line moves into a surface, and a surface moves into a body
3. The nib quickly slides on the paper and writes out one English letter after another, which explains (inching to form a line); when the wheel rotates, it looks like a whole round surface, which explains (linear to form a surface); a right triangle rotates around its right side to form a cone, and explains (surface to form a body)
4. The sides and the bottom of the cylinder intersect into (2) lines, which are (closed) lines. (circle)

It is known that the perimeter of a right triangle is 30cm and the area is 30cm square, then the oblique side of the right triangle is long____ CM.
If the perimeter of an isosceles triangle is 16cm and the height of its bottom is 4cm, then the length of its bottom is ()
A 3 B 4 C 5 D 6
If the perimeter of a right triangle is 2 ＋ 6 and the hypotenuse is 2, the area of the triangle is ()
A 0.25 B 1 C 0.5 D 2√3

The answers are (guaranteed to be correct) in turn:
1. 13 (5,12,13 on three sides)
2. 6 (5,5,6 on three sides)
3. C (there is no need to calculate the trilateral, the whole is substituted by S = 1 / 4 [(a + b) 2 - (A2 + B2)])
I don't give you any points. I'll send you the intermediate data again,

(1) How many degrees does the minute hand of the clock turn in one minute? How many degrees does the hour hand turn in one minute?
(2) Calculation: (the results are expressed in degrees, minutes and seconds) 90 ° - 28 ° 16 ′ 18 ″ × 2
(3) Calculation: (the results are expressed in degrees, minutes and seconds) 36 ° 48 ′ 3
(4) On the same day, from 15:10 to 15:30, how many degrees did the minute hand turn? How many degrees did the hour hand turn?

(1) How many degrees does the minute hand of the clock turn in one minute? How many degrees does the hour hand turn in one minute? One turn of the clock is divided into 12 large grids and 60 small grids, with a total of 360 degrees. In one minute, one turn of the second hand = 360 degrees, one small grid of the minute hand = 360 △ 60 = 6 degrees, and one twelfth small grid of the hour hand = 6 △ 12 = 0.5 degrees

Some space geometry problems
A line passing through a point outside the line is parallel to the line__ strip
A plane passing through a point outside the line parallel to the line has a__ individual
A line passing through a point outside the line and perpendicular to the line__ strip
The plane passing through a point outside the line and perpendicular to the line has__ individual

A line passing through a point outside the line is parallel to the line_ 1_ strip
A plane passing through a point outside the line parallel to the line has a_ Countless_ individual
A line passing through a point outside the line and perpendicular to the line_ 1_ strip
The plane passing through a point outside the line and perpendicular to the line has_ 1_ individual

How to do the problem of space geometry
Can ask to learn space geometry. Do line parallel vertical and so on how to do. Just can't do auxiliary line

This should be the expansion of your own spatial imagination. When you do these questions, the relationship between lines doesn't feel like it. But if you give full play to your spatial imagination, you will feel that it is in line with the spatial position relationship, and when you do auxiliary lines, you should pay attention to the real virtual relationship of lines. The meaning expressed by solid lines and dotted lines is different

Topics of space geometry
When a plane passes through a point (1,2,3), its intercept is equal on the positive x-axis and y-axis. When the intercept of the plane is what, the volume of the plane and the three coordinate planes is the smallest?

Proof: the angles formed by two parallel lines and the same plane are equal
The next one is judgment
Two planes perpendicular to the same line are parallel to each other ()
I think it's right, but I don't know where it is right, because I haven't found any counter examples, so I ask for advice

The first problem is: the straight line L1 ‖ L2, and the angles between L1 and L2 and plane a are α and β respectively. Proof: α = β. [proof] 1. Let L1 and L2 intersect plane a and B.2 respectively. Take points c and D on L1 and L2 respectively, so that AC = bd.3. Let C and D lead the vertical lines of plane a respectively, and the vertical feet are e, F. ∵ AC ‖ BD

Proof problem, space geometry
It is proved that the longest edge of a tetrahedron ABCD must have an end point, and the sum of the lengths of the other two edges derived from it is greater than that of the longest edge

If AB is the longest edge of a tetrahedron ABCD, then ABC, abd and ACD are all triangles
AC + BC ＞ AB, AD + BD ＞ AB, AC + AD + BC + BD ＞ 2Ab can be obtained by combining the two formulas
If AC + ad ≤ AB, then BC + BD must be greater than AB, and vice versa
So the sum of the lengths of the other two edges is greater than that of the longest edge

Two geometric problems
The line AB is divided into two parts: 3:5 by point C and 7:5 by point D. given that CD = 2.5cm, there are three lines to find the length of ab. given that ABC knows the length relationship between them as: A is two-thirds of B and C is three-thirds of B, what is the relationship between AC?

From the problem, we know: AC: CB = 3:5. (AC + CB): CB = (3 + 5): 5. AB: CB = 8:5cb = (5 / 8) AB; ad: DB = 7:5 (AD + dB): DB = (7 + 5): 5ab: DB = 12:5db = (5 / 12) ab. ∵ ad > AC. ∵ cb-db > 0. Cb-db = (5 / 8) ab - (5 / 12) AB = CD = 2.5