How to understand obtuse triangles and what is the definition of obtuse triangles

Need to be understood in conjunction with Cartesian axes Have you ever been on a Cartesian axis?

Obtuse trianglesDefinition: A triangle with an angle that is obtuse is an obtuse triangle.

Features:1The obtuse angle is greater than ninety degrees and less than one hundred and eighty degrees.

2.In an obtuse triangle, the sum of the two acute angles is less than the obtuse angle number.

Acute triangle.

Definition: A triangle with three acute angles is called an acute triangle.

Properties: Acute angles: In a triangle, all three corners are acute angles.

Tips for learning math.

1. Be good at thinking when learning mathematics, and the answers you come up with are far more impressive than the answers told by others.

2. Do a good job of preview before class, so that you can better digest and absorb the knowledge points when you take math class.

3. Mathematical formulas must be memorized, and they must be able to derive and draw inferences.

4. The most basic thing to learn mathematics well is to master the knowledge points of the textbook and the exercises after class.

5. 80% of the scores in mathematics are in the basic knowledge, and 20% of the scores are difficult, so it is not difficult to score 120 points.

Triangles can be divided into acute triangles, right triangles and obtuse triangles according to the size of the angles;

In an obtuse triangle, one of the three angles is called an obtuse triangle with an angle greater than 90 degrees;

An obtuse triangle means that in a triangle, there is an inner angle with a degree greater than 90 degrees, then the triangle is an obtuse triangle.

The definition of an obtuse triangle is that there is an obtuse triangle called an angle greater than 90 degrees.

The formula for calculating the tangent of the obtuse angle is sine, cosine:

sinusoidal: sina = sin(180°-a);

Cosine: cosa=-cos(180°-a);

Tangent: tana=sina cosa. where a is the desired obtuse angle.

When the angle varies between 90° and 180°, the sine value decreases (or increases) with the increase (or decrease) of the angle, and the cosine value decreases (or increases) with the increase (or decrease) of the angle; The tangent value increases (or decreases) with the angle, and the tangent decreases (or increases) with the angle;

The secant value increases (or decreases) with an increase (or decreases) the angle, and the secant value increases (or decreases) with an increase (or decrease) with the angle.

Blunt nature. 1. The obtuse angle is composed of two rays.

2. The obtuse angle is a kind of inferior angle.

3. The obtuse angle must be the second quadrant angle, and the second quadrant angle is not necessarily an obtuse angle.

4. In the trigonometric values of obtuse angles, the sine value (sin) is a positive value, and the cosine value (cos), tangent value (tan), and cotangent value (cot) are negative values.

Trigonometric functions that are formulated into acute angles using the co-angle formula or the complementary angle formulation:

a is an obtuse angle: then -a, or a-2 are both acute angles.

sin(a)=sin(π-a)

cos(a)=-cos(π-a)

sin(a)=cos(a-π/2)

cos(a)=-sin(a-π/2)

An obtuse triangle has one obtuse angle and two acute angles, such that its obtuse angle is .

sinα =sin(180°-α

cosα=-cos(180°-α

tanα=-tan(180°-α

cotα=-cot(180°-α

secα=-sec(180°-α

cscα=csc(180°-α

Two of the obtuse triangles are high on the outside of the obtuse triangle and the other inside the triangle. In an obtuse triangle, the sum of the two acute angles is less than the obtuse angle number.

Obtuse trigonometry is the content of the ninth grade of middle school mathematics.

The content includes sine, cosine, and tangent, which will also be learned in high school, and will be taught in more detail than in junior high school. Trigonometric function is usually defined as the ratio of the two sides of a right triangle containing this angle, and can also be defined equivalently as the length of various line segments on a unit circle.

Trigonometric functions are the simplest content in high school mathematics, in high school a total of three trigonometric functions, sine function, cosine function, tangent function, students should study carefully, learn their images and properties, learn related formulas and trigonometric transformations, this class students must overcome the habit of laziness.

Trigonometric functions play an important role in the study of the properties of geometric shapes such as triangles and circles, and are also a fundamental mathematical tool for the study of periodic phenomena. In mathematical analysis, trigonometric functions are also defined as infinite series or solutions to specific differential equations, allowing their values to be extended to arbitrary real values, even complex values.

Common trigonometric functions include sine, cosine, and tangent. In other disciplines such as navigation, surveying and mapping, and engineering, other trigonometric functions such as cotangent function, secant function, cosecant function, sagittal function, cosagittal function, semi-sagittal function, semi-cosagittal function, and other trigonometric functions are also used.