It is nothing more than finding the nature of a triangle. The practical problem in real life is finding the slope. ...

But in high school, tan is as important as sine theorem and cosine theorem ~!

First of all, Tan Can should be used to find the included angle between two straight lines, which is especially important in analytic geometry ~!

Secondly, when learning derivatives, some teachers use tan to transition ~!

Trigonometric function will occupy a considerable position in both the senior high school entrance examination and the college entrance examination, and will never decline!