Mathematics is used comprehensively 40

What are you asking? I don't know how to ask my classmates or teachers

Ask for it, I've been counting it for a long time, but I haven't figured it out, and your first question is 60 degrees.

Zhengyu Xuan turned, the first question will be simpler, and the second question will be simpler.

I can't remember if the normal and cosine theorems were from high school, but I do remember that junior high school students should have mastered them.

In addition, the second one you said is a theorem I forgot, three words, junior high school math competition has an impression.

Whether it's junior high school or high school, it is recommended that you can master a little more, which is beneficial.

It's all supplemented by high school, and I also just started school. The second one is deduced from Yu Xuan's theorem, and it is recommended that you come and visit here.

24 5 to positive infinity [where AB is the smallest when it is perpendicular to BC, it should be B*Sina = 24 8, and the length of C has no upper line. (where A corresponds to angle A, B corresponds to angle B, and C corresponds to angle C).

sina*sina+cosa*cosa=1

The sine value of the inner angle of the triangle must be positive, and when the cosine value is known, sina = (1-cosa*cosa).

Enter =cos(radians) in the cell

tan45=1, the sum of squares of the positive coss function is 1, and the homogeneous (quite common) loga1=0

In fact, it is not only the magic of 1, but also the other sum is a fixed value, which can be "multiplied by 1 transformation", and you need to make up for it yourself.

1 Many of the relationships in the question appear at the same time.

2 In a triangular relationship, tan45=1

3 A patchwork of x+1 x or something like in the proof of mean inequalities.

In the triangular relationship, tan45=1 solves the tangent problem.

In trigonometric functions, the sum of squares of the positive coss function is 1, and the homogeneous (quite common) loga1=0

The proportional sequence is summed, and the case with a common ratio of 1 is written separately.

In trigonometric functions, the sum of squares of the positive cospin function is 1

x,y are both positive,x+y=1; Solve for a minimum value of 1 x+1 y?