There are several times in 24 hours a day when the minute hand is at a 90 degree angle to the hour h

In total, there are 44 right angles, and the reasons are as follows:

Since the hour hand rotates 30° in one hour, it rotates in 1 minute, and the minute hand rotates 6° per minute. Let the hour hand be at right angle to the minute hand after x minutes, then there is the equation x(6°. If there are n times, then n=88 is solved.

In these 88 times, the hour and minute hands are angled at 90°, 180°, 270°, and 360° respectively, of which 180° and 360° are not satisfactory, so there are a total of 44 right angles.

Quartz Clock Principle:

The core of the quartz crystal sensor is the sensing element - piezoelectric quartz wafer. It works on the principle of piezoelectric effect.

That is, when the quartz crystal is subjected to mechanical stress in certain directions, an electric dipole is generated.

Conversely, if a voltage is applied to a quartz in one direction, it will be deformed in a specific direction, a phenomenon known as the inverse piezoelectric effect.

If an alternating electric field is applied to a quartz crystal, the crystal lattice will produce mechanical vibrations, and when the frequency of the applied electric field coincides with the natural oscillation frequency of the crystal, the crystal resonance occurs.

Due to the strength of the electric field produced by quartz crystals under pressure.

It is very small, so that only a weak applied electric field is required to produce deformation, a property that makes piezoelectric quartz crystals easily resonant when excited by an applied alternating electric field.

Its oscillation energy loss is small, and the oscillation frequency is extremely stable. This, combined with quartz's excellent mechanical, electrical and chemical stability, has made it a magnet for quartz clocks, electronic watches, televisions, computers, etc., and digital circuits since the 40s.

The frequency reference element in question.

An interesting property of quartz crystals is that when a positive current is introduced on one side and a negative current is introduced on the other side, the negative current side shrinks and bends into a U-shape.

If positive and negative currents are introduced alternately on both sides of the quartz crystal, the quartz crystal will oscillate. Quartz crystals are timed according to this oscillation. The quartz crystal built into the PC oscillates 14,318,180 times per second. That's how quartz clocks work.

Because it is 48 times, the reason: because the hour hand rotates 30° in 1 hour, it rotates in 1 minute, and the minute hand rotates 6° per minute

Let the hour hand be at right angles to the minute hand after x minutes, then there is an equation.

x(6° How many times will the needle differ by a multiple of 90° in 24 hours? There are n times, then.

This results in n=88

In these 88 times, the angles of the hour hand and the minute hand are 90°, 180°, 270°, and 360° respectively, of which 180° and 360° are not satisfactory, so there are a total of 44 right angles in 12 hours, and there are 9:00 and 3:00 in 12 hours, there are two, and there are 24 hours, there are 4 times, so 44 + 4 = 48 Answer: 48

96 times, the minute hand goes 1 lap for 1 hour, which is 360 degrees, and there are only 4 times at a 90-degree angle, 24 hours x 4 = 96

How many times of the day are the hour and minute hands at 90 degrees angle? respectively.

The minute and hour hands are 48 in the 90s, 2 per hour. Special cherry blossom debate moments such as 3 o'clock, 9 o'clock, 15 o'clock, 21 o'clock cover quickly into 90 corners.

After 4 o'clock, a total of x minutes elapse from the hour hand to the second 90-degree angle of the minute hand.

Then: x-(4*5+x*(5 60))=90*(60 360)x-(20+x 12)=60 Qingshichun 4=15x-x 12=15+20=35

x*(11/12)=35

x = 35 * 12 11 = 420 11 = 38 (2 11) points.

After 4 o'clock, 38 (2 11) minutes elapsed from the hour hand to the second 90-degree angle of the minute hand.

Summary. The minute hand goes 1 square per minute, that is, 360 60 = 6 degrees, the hour hand walks (360 12) 60 = degrees, that is, 1 12 squares at 4 o'clock, the hour hand and the minute hand are 20 squares apart, that is, 20 6 = 120 degrees, at this time, it is regarded as chasing the problem, the speed difference = degrees, then it becomes 80 degrees, and the time used: (120-80) minutes, 7 minutes and 16 seconds, the second time:

When the minute hand exceeds 4, then the minute hand goes 120 + 80 = 200 degrees, and the time it takes is 200 minutes and 22 seconds, that is, at 4:7:16 and 4:36:22, the angle formed by the hour and minute hands is 80 degrees.

Within 24 hours, when is the angle formed between the hour hand and the minute hand 80 minutes hand goes 1 block per minute, that is, 360 60 = 6 degrees, the hour hand goes (360 12) per minute, 60 = degrees, that is, 1 12 grids 4 o'clock, the hour hand and the minute sail hand are 20 grids apart, that is, 20 6 = 120 degrees, at this time, it is regarded as chasing the problem, the speed difference = degrees, then it becomes 80 degrees, the time used: (120-80) minutes, 7 minutes and 16 seconds, the second time: when the minute hand exceeds 4, the minute hand goes 120 + 80 =200 degrees is changed by 200 minutes and 22 seconds, which means that at 4:07:16 and 4:36:22, the angle formed by the hour and minute hands is 80 degrees.

The angle of mon is equal to a 2

How to write the process?

Your problem should be equal to A when BOC, and OM divides BOC equally, otherwise you can't do this problem.

Look at the angular bisector of AOB when you look at om** for yourself.

That diagram is wrong.

Not rated at all.

How to write the process of the question?

Then you have to give me the correct picture, or I won't be able to describe the corners here.

It's not like I said A should be in the position of C.

This is followed by y+a

Let's assume that from 12 o'clock after x minutes, the hour hand and minute hand are 90 degrees for the first time, 360 x 60-360 x 60 12 = 90x = 180 11 minutes 12 later, when the hour hand and minute hand are 90 degrees for the second time, and Y minutes have passed: 360 (y+180 11) 60-360 (y+180 11) limb sells 60 12 = 90y = 360 1112, and then the second time the hand is 90 degrees.

The minute hand turns in one minute: 360 60 = 6 degrees.

The hour hand turns in one minute: 30 60 = degrees.

180 11 minutes.

24 hours = 24x60 = 1440 minutes.

44 times.

At 7:55 p.m., the angle between the hour and minute hands was equal to 120 degrees.

This is not right with Pei.

At 8 a.m., the angle between the hour and minute hands is equal to 120 degrees.

It should be 44 times bond base.

It can be seen as a matter of chasing the minute and hour hands.

Every two times into a time interval of 90 ° is. Hour.

Then, 24 manuscript stools (6 11) = 44 times is the correct answer.

Let the distance of a rough circle be 1

The speed of the minute hand is 1

The speed of the hour hand is 1 12

Every two times at 90°, i.e. the minute hand travels more than the hour hand.

Then you get the formula.

If the time is calculated at 90°, counting the first and last two times, then it is 45 times. 44 times in other cases.