Kindergarten number triangle problem, ask for help number triangle method! Thank you! 40

When counting, start with the smallest in one direction (clockwise or counterclockwise) and slowly expand the range.

For example, the first one has 12 small ones, and then it expands into a medium triangle of four small triangles, and then there are six of them, and then there's a large triangle of nine small triangles, and there are two, so there are 20 of them.

The second one, there are 10 smaller ones, and then you can see that one side of the pentagram and two of the outer edges of the pentagonal shape can form five triangles, and each of these five triangles can be split into two smaller triangles, so that there are 5+5*2, and then the two sides of the pentagram and one of the outer edges of the pentagonal star can form five triangles, so there are 30 of them.

The second picture is not very easy to describe, and I hope it won't be too dizzy.

The trick to this kind of problem is to have a clear idea, don't see one by one, count one by one, it's easy to count and mix up, and distinguish the situation.

For the sake of my sake, hurry up my answer.

First find 1 triangle, then find a large triangle of 4 triangles, and then find a triangle of 9 triangles. Be careful, attentive.

Look for them one by one.

What's the way to do this?

What is this for, what are you asking for? Is it asking for something, is it a number or. Please explain.

Choice C Thought Process: The condition for forming a triangle is that the sum of the two sides of the triangle is shorter and must be greater than the third side.

The title says "no matter what kind of truncation there is, there always exists", so we can rule it out by citing a truncation that does not form a triangle.

First of all, look at n=3, if it is truncated into 1, 1, 98, it will not form a triangle.

Looking at n=4 again, if it is truncated into 1, 1, 3, 95, it will not form a triangle.

If we look at n=5, then no matter how we cut it, there are always three numbers that make up a triangle, such as (1,1,1,...; 1, 2, 1, 1, etc.).

o is the round lead center of the trapped-acacia triangle abc circumscribed circle.

The opposite arc of the angle A is equal to the opposite arc of the angle boc, so boc = 2 a = 140 degrees.

o is the center of the circumscribed circle of the triangle abc.

A and BOC's blind arc of Tangerine Chang is the same circle and one arc.

A is the same angle of the circle, and BOC is the heart angle of the circle.

boc = 2∠a = 140°

Solution: Let the edge of this polygon be the number n, and the degree of the undercalculated inner angle is According to the question: (n-2) 180° 1125° then (n-2) 180° 1125° and 0° 180°

0° (n-2) 180° 1125° 180° solution:

and n is a positive integer.

Eligible n is 9

This Senjiao polygon is a nine-sided shape, and the sum of the internal angles is: (9-2) 180° 1260°Answer: This polygon is a nine-sided polygon, and the inner angle that he undercounts is 135°.

Analysis: A polygon can be divided into several triangles, right? The inner angle of the triangle and 180 °, Huai is good, look at the topic, we find that when 180 ° 6 = 1080 °, 180 ° 7 = 1260 °, the former does not meet the requirements of the question, the answer ridge then this less angle Qingming infiltration is 1260 ° - 1125 ° = 135 °

Solution: Derived from the question:

So the angle of the less added is 135°

Proof: Extending bp to ac in q, the two sides of the triangle and greater than the third side, ab+aq bq bp+pq, and pq+qc cp, the two inequalities are added.

ab+aq+pq+qc bq+cp bp+pq+cp, both sides are about pq, that is, ab+aq+qc bp+cp, that is, ab+ac bp+cpProven.