Fundamental Mathematics/Geometry

Points distributed on a graph.

Line functions drawn on a graph.

Geometry is a branch of mathematics concerned with questions of shape, size, relative position of figures, and the properties of space. A mathematician who works in the field of geometry is called a geometer.

Points

Points are considered fundamental objects in Euclidean geometry.

Lines

By Euclid's axioms, a line can be drawn from 2 points. Example through 2 points A and B, we can draw the line AB.

A---------------B

Lines of interest

Lines	Definition	Piture
Perpendicular lines	Two lines intecsect at a point to form an angle 90o	${\overline {AB}}\perp {\overline {CD}}$
Parallell lines	Two lines do not intecsect each other	${\overline {AB}}{//}{\overline {CD}}$
Vector	Line with its direction	${\vec {AB}}$

Angles

Two lines intersect at a point to form an angle between 2 lines . Example Line AB intersects line AC to form an angle A between 2 lines. Angle has a symbol $\angle$. Angles are measured in degrees (^o) or radians (Rad). Failed to parse (unknown function "\rad"): {\displaystyle \rad}

Example angle 90 degree is π radian

$\angle A=90^{o}={\frac {\pi }{2}}Rad$

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  Acute angle , angle less than 90°

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  Right angle , angle equals to 90° (1/4 vòng tròn);

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  Obstuse angle angle greater than 90° and less than 180°

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  Góc bẹt là góc 180° (1/2 vòng tròn).

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  Góc phản là góc lớn hơn 180° nhưng nhỏ hơn 360°

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  Góc đầy là góc bằng 360° (toàn bộ vòng tròn).

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  Góc khối

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  Đường phân giác

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  Chia đôi một góc bằng compa và thước kẻ

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  Góc đối đỉnh

Geometric figures

Polygons

Polygons are shapes of <$n$ sides and include:

Further reading

•  Calculus
•  Angle