Love lasts a lifetime

When He Yu guided students to study the inclination angle of a straight line, he particularly emphasized;

"Students must remember that the angle between a straight line and the positive direction of the x-axis and the upward direction of the straight line is called the inclination angle of the straight line.

This is critical to the calculation of the angle between two straight lines that we will study in the next step. He gave the students a minute to look at the picture carefully, and then said:"We follow this rule when calculating the slope of the straight line." ,

Now ask the students to read carefully, guess, and calculate how the angle between two straight lines is calculated.

Find out each letter in the calculation formula and what the calculation symbol is."

After the students read the textbook, He Yu wrote the formula for calculating the angle between two straight lines on the blackboard. tanθ=|k1-k2/1+k1k2|

He Yu asked a female classmate;"What does tanθ in the formula represent?"

The student replied;"tanθ represents the tangent of the angle θ between two straight lines."

"So what do k1 and k2 represent?"He Yu asked.

The classmate replied;"It represents the slope of two straight lines."

"Colleagues said, is his answer correct?"He Yu asked.

Many students said:"That's right!"'

He Yu continued:"Then please students, let's recall how the slope of a straight line is calculated."

He Yu put the general formula of the straight line equation: Ax+By+C=0 (A≠0B≠0) was written on the blackboard.

He asked,"Does anyone know how the rate is calculated?"

A student in the back row quickly walked up to the blackboard without raising his hand and wrote it accurately on the blackboard; k=-A/B

He pointed at the calculation formula and said,"A is the coefficient of X in the straight-line equation. B is the coefficient of the Y term."

He Yu asked,"Students!

Is what he wrote correct?"

"Quite right!"

Many students answered in unison.

He Yu said happily:"This classmate is very courageous. Not only did he not raise his hand, he took the initiative to write the slope calculation formula in a very standardized way. He also quickly completed the calculation without thinking. The letters in the formula speak very clearly.

It's really rare.

I like this kind of classmate and hope that all my classmates can learn from him."

Some teachers who were listening to the class began to make a commotion again. They were whispering again, 'The students He Yu asked to answer the questions must be outstanding students. Otherwise, why did everyone answer you correctly?’

‘Even if he is not an outstanding student, he is still a student who he has taught beforehand.

Otherwise, why not only write the calculation formula in a very standardized way, but also spell out the letters in the calculation formula so clearly?’

‘Why don't you just stand up and answer?

And without the teacher's permission, he even ran up to write.

Not only did He Yu not criticize this approach, he also vigorously commended it?

How is this appropriate?

If every student did this, wouldn't the class be in chaos? '

The leaders of the Education Bureau glanced at these teachers, and their meaning was very clear!

One teacher quickly pressed down the other teacher's raised hand.

There was a teacher who was dissatisfied with the gesticulating teacher and glanced sideways. And secretly accused:"Such a teacher who doesn't understand etiquette is so shameless!"

Is he more capable than Teacher He? '

Really; did He Yu make a mistake, or was there something wrong with the student's answer? It's hard to figure out how to point fingers.