I can t learn similar triangles, and then how to learn the acute triangle ratio

Don't be afraid, it's a holiday, it's much better to go to school and learn from the teacher, do more questions, I believe you will succeed, don't be discouraged.

The three angles are equal, that is, the degree of each angle is: 60°, the definition of an acute triangle is that the three angles are less than 90° (including 90° without pinning), which meets the conditions of an acute triangle, so all three angles are equal and are acute triangles. Zhen Douqing.

Hopefully).

1) Draw and know that there is an equilateral triangle, so the angle a = 60 degrees.

Therefore, b = 2 3 and c = 4 3

2) You should be talking about right triangles.

ab=60,a^2+b^2=13^2

Therefore, a=12, b=5, sina=12 13 hope it helps you.

Definition of similar triangles:

Two triangles with equal angles and proportional sides are called similar triangles.

If the three sides correspond to a, b, c and a, b, c: then:

a/a=b/b=c/c

That is, the corresponding proportions of the length of the three sides are the same.

This is junior high school math knowledge].

A straight line parallel to one side of the triangle cuts off the other two sides of the line, and the resulting triangle is similar to the original triangle. (This is the theorem of the similarity triangle determination, which is the basis for the following determination method proof.) The proof method of this lemma requires the proof that the parallel lines are proportional to the line segments).

Define the verdict. Two triangles with equal angles and proportional sides are called similar triangles.

Decision Theorem 1: If the two angles of a triangle correspond equally to the two angles of another triangle, then the two triangles are similar (aa).

Decision Theorem 2: If the two corresponding sides of two triangles are proportional and the corresponding angles are equal, then the two triangles are similar (SAS).

Decision Theorem 3: If the three corresponding sides of two triangles are proportional, then the two triangles are similar (SSS).

Decision theorem 4: If the three sides of two triangles correspond to parallel, then the two triangles are similar.

Decision theorem 5: In two right-angled triangles, the hypotenuse is proportional to the right-angled side, then the two triangles are similar.

For example, two triangles with equal sides are congruent triangles, which can be obtained by analogy, and two triangles proportional to three sides are similar triangles.

Ask. What should I do if I can't find a suitable triangle when I see a line segment.

When I was in junior high school, I only learned the trigonometric ratio of special angles, and an acute triangle is a triangle where every angle is an acute angle.

2.exists, and the sine cosine can be represented in the unit element.

cosa=-1/√13

Remind you to pass d for perpendiculars on both sides, and for a perpendicular line for bc.