How to measure the height of flagpole? Design scheme and solution

Sunny days can be measured by shadow height ratio method. Choose a sunny morning or afternoon, first measure the height of a standard pole (such as 1m or 2m), then stand on the ground and measure the length of the pole shadow to get the ratio of the pole shadow to the height. At this time, the shadow length of the flagpole is measured immediately, and the height of the flagpole can be calculated by the ratio.

Students are divided into groups, and some use props to demonstrate the practice and explain how to construct similar triangles, and the teacher will guide them. In addition, the student representatives in the group explained on the blackboard: according to (pictured) △ Abe △ CDB.

List the proportional formula AB to get BE, and point out that the data to be measured are: the height of the classmate standing at the top of the shadow of the flagpole, his shadow length and the shadow length of the flagpole. The height of the CD can be obtained by substituting the measured data.

Extended data

Solution:

You have made a wonderful analysis of the shadow method, but we consider that it is impossible to measure without sunlight. Some students also said that you can create shadows with electric lights at night, no problem. But this method still has some limitations, so can it be measured by other methods? Students will say yes and demonstrate their methods in groups. ?

Some students will use props to show their practices and explain how to build similar triangles. Teachers will guide them. Another student representative will point out on the blackboard that when the top of the flagpole and the top of the flagpole are just in a straight line with the eyes, because the straight line AB where people are located is parallel to the pole and the flagpole, the perpendicular line where the flagpole CD intersects with the point A where the eyes are located will intersect with the flagpole CD at N and the flagpole EF at M..