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Super math teacher Chen
The minute hand speed is 1 grid/minute, that is, 6 degrees/minute; The speed of the hour hand =112 grid/minute, that is, 1/2 degrees/minute.

Suppose the story-telling time starts at 7: 00 x, then the angle between the hour hand and the "6" scale is (x/2+30) degrees.

The included angle between the minute hand and the scale "6" is (30-x)*6 degrees, and the sum of them is 90 degrees, so x = 240/1,which is about 2 1.8 minutes.

That is to say, the time to start telling stories is 7: 00, 2 1: 48.

Let the story-telling end time be 8: 00 x minutes, then the angle between the hour hand and the "6" scale is (x/2+60) degrees.

The included angle between the minute hand and the scale "6" is (30-x)*6 degrees, and the sum of them is 90 degrees, and x = 300/1/,which is about 27.3 minutes.

That is to say, the time to start telling stories is 7: 27: 18 seconds.

Another time in the middle is from 7: 30 to 8: 00, and the needles are at a 90-degree angle. If it is set to 7 o'clock x minutes, the included angle between the hour hand and the "6" scale is (x/2+30) degrees.

The included angle between the minute hand and the "6" scale is (x-30)*6 degrees, and the two are subtracted to be 90 degrees, so x=600/ 1 1, which is about 54.5 minutes.

That is, the time is 7: 54: 30.