1, as shown in the figure, the angle that can be marked with letters in (1) graph is _ _ _ _ _ _ _ _ _ _.

(2) Please write the angle whose vertex is A in the picture. They are.

2. As shown in the figure, the angle formed by the open feet of the compass is ()

A, right angle b, obtuse angle c, right angle d, acute angle

3. Among the following angles, the obtuse angle is ()

A, rounded corners b, flat corners c, rounded corners d, flat corners

4, as shown in the figure, the following statement is correct ()

The direction of a and OA is northwest.

The direction of b and OB is 60 from south to west.

The direction of c and OC is 40 east-south

The direction of D and OD is 65 North-East.

5. Calculation: _ _ _ _ _ _ _ _ _ _ _ _; =________ ; ________

◆ Typical case analysis

Example: (1) As shown in the figure, the following statement is incorrect ().

A, OA direction is 30 north east? B, OB direction is 15?

C, OC direction is 25? The direction of d and OD is southeast.

(2) At sea, the lighthouse is located 40 degrees east of the north of the ship, so the ship is located in the lighthouse ()

A, 50 degrees southwest b, 40 degrees southwest

C, 50 degrees east of north, 40 degrees east of north.

Solution: (1) A. Correct statement: OA direction is 60 north-east .

(2)B (as shown on the right)

Comment: (1) The key to the bearing problem is two elements: bearing and angle.

(2) This example mainly focuses on "Where is this ship located in this lighthouse", and it is easy to solve this problem from the picture.

◆ Homework after class

● Expand and upgrade.

1. A fishing boat is at sea. Seen from the ship, the lighthouse is located at 250 degrees northeast, so seen from the lighthouse, the ship is located at ().

A 650 degrees southwest, 650 degrees southwest, 250 degrees southwest and 250 degrees northwest.

2. The correct number of angles in the picture below is ().

a， 1 b，2 c，3 d，4

When the clock points to 2: 30, the angle formed by the hour hand and the minute hand is. From 2: 30 to 2: 55, the hour hand turned _ _ _ _ _ degrees and the minute hand turned _ _ _ _ _ _ _ degrees.

4. Write the calculation results directly:

′; 28800〞= = ′。

Someone walked 20 meters northeast from A to B, and then walked 20 meters southeast from B to C.. At this point, point C is in the direction of point A.

6. 18 When someone goes out to buy something, the angle between the hour hand and the minute hand on the clock is 1 10. When he got home near 19, he found that the angle between the hour hand and the minute hand was 1 10. How long did he stay outside?

7. As shown in the figure, a student who serves in the track and field sports meeting has to go back and forth from the starting point A, the ending point B(A and B are located in the east and west respectively) and the reporting place C. He sees that point C is 60 east-north at point A and 45 west-north at point B..

(1) Determine the location of check-in location c;

(2) Only the scale is used as a tool. If you want to know how many meters this student has to walk from the registration place C to the starting point A of 100 meters (without considering other factors), please tell me your method (without specific calculation).

● Experience the senior high school entrance examination

1, (adapted from Tianshui examination questions in Gansu Province in 2009) If an angle is 30, it should be _ _ _ _ when observed with a telescope of 10 times.

2. (Adapted from the senior high school entrance examination in Jiaxing, Zhejiang Province in 2009) In the following four pictures, those that can represent the same angle in three ways are ∠ 1, ∠AOB and ∠O are ().

As shown in the figure, there is a clock on the ground, and the scale of the 12 thick line segment on the clock face is the position pointed by the hour hand (short hand) at the hour. According to the position indicated by the hour hand and minute hand (long hand) in the figure, the time displayed on the clock face is _ _ _ _ _ _ _ _ _ _ _ _ _ _.

Reference answer:

◆ In-class detection

1 、( 1)∠B、∠C； (2)BAC，DAC，BAD 2，D 3，B

4、A 5、870 18 '，87.05，87.5

◆ Homework after class

● Expand and upgrade.

1, C 2, B 3, 1050, 12.5, 150 4,12,20,8,4805, due east.

6. If the hour hand goes home from this person X, then the minute hand goes (2× 1 10+X). From the meaning of the question, X = 20, because the hour hand goes 30 per hour, so (hour), that is, it takes 40 minutes for this person to go out. .

7.( 1) As shown in the figure.

(2) The lengths of 2)AB and AC can be measured with a scale, and the actual distance between point A and point C can be calculated through the proportional relationship, so that we can know how many meters it takes to go back and forth between the check-in place C and the starting point A of 100 meters.

● Experience the senior high school entrance examination

1、30 2、D 3、9、 12

Children who love learning hope that their sister's answer can be adopted!