2 n straight lines intersect at most one intersection point and divide the plane into several parts at most.
Three known points can determine a straight line and four known points can determine a straight line.
4 known ∠ AOB = ∠ COD = 90, then ∠AOC=, according to
5 If AB=5, CB=3, A, B and C are on the straight line L, then AC = A..
6 if c is a point on a straight line AB, AB=a, m and n are the midpoint of AC and BC respectively, then c.
MN= O B
When the clock reaches 3: 00, 15, the angle between the hour hand and the minute hand is degrees.
8 As shown in the figure, each face of a cube is marked with 1, 2, 3, 4, 5, 6 respectively, and press D.
The graphics displayed in three states of cubes A, B and C in the drawing can be deduced. The number is
5 1 3
4 1 2 3 ? five
B.C.
9 Line AB=3.5cm, extending AB to C makes BC=2.5cm, and then conversely extending AB to D makes AD=4cm, and M and N are the midpoint of BC and AD respectively, then MN=
10 Fold the rectangle ABCD along AE, so that D falls at F on the side of BC. If BAF = 60, DAE =
1 1 indicates the angle formed by two rays at point O = 1, in the direction of east-south 15 and east-north 25. It is known that the angle AOB=90 degrees, OC is a straight line, and OM and ON bisect the angle BOC (angle BOC
2. Draw a ray of 3 angles, 2 rays of 6 angles, 3 rays of 10 angle and 4 rays of 13 angle. If you draw n rays in ∠AOB, how many angles will be formed?
3. The bisector of ∠AOB is OM, ON is a ray in ∠MOA, OG is a ray outside ∠ AOB, ∠GOB is a right angle, and everything else is in ∠GOB. After careful analysis, a classmate came to the conclusion that a relationship is ∝. If it is correct, please write down the process of reaching this conclusion.
4. Stack a pair of right-angled triangular plates together, so that the right-angled vertex coincides with point O, then ∠ AOB+∠ Doc = ().
5. Student A starts from A and walks 75 northeast 10 m to B, while student B starts from A and walks southwest 15 m to C. Then the included angle between AB and AC is ().
6. Given that point O is on straight line AB, the length of line segment OA is 4cm, the length of line segment OB is 6 cm, and e and f are the midpoint of line segments OA and OB respectively, then the length of line segment EF is () cm.
7. ∠AOB = 90, OC is the light outside ∠ AOB, OE is the bisector OF ∠BOC, and of is the bisector of ∠AOC. The number of times to find ∠EOF.
I hope the landlord chooses me, thank you.