# What is the difference between Euclidean geometry and projective geometry?

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## What is the difference between Euclidean geometry and projective geometry?

Intuitively, projective geometry can be understood as only having points and lines; in other words, while Euclidean geometry can be informally viewed as the study of straightedge and compass constructions, projective geometry can be viewed as the study of straightedge only constructions.

## Is projective geometry hard?

Technically, projective geometry can be defined axiomatically, or by buidling upon linear algebra. Although very beautiful and elegant, we believe that it is a harder approach than the linear algebraic approach.

## What is a formula of geometry?

The geometry formulas are used for finding dimensions, perimeter, area, surface area, volume, etc. of the geometric shapes. Geometry is a part of mathematics that deals with the relationships of points, lines, angles, surfaces, solids measurement, and properties.

## Why is geometry so hard?

Why is geometry difficult? Geometry is creative rather than analytical, and students often have trouble making the leap between Algebra and Geometry. They are required to use their spatial and logical skills instead of the analytical skills they were accustomed to using in Algebra.

## How are equilateral triangles different from spherical triangles?

Here are some examples of the difference between Euclidean and spherical geometry. In Euclidean geometry an equilateral triangle must be a 60-60-60 triangle. In spherical geometry you can create equilateral triangles with many different angle measures.

## Are there any parallel lines in a geodesic sphere?

No parallel lines: Any two geodesics will intersect in exactly two points. Note that the two intersection points will always be antipodal points. Sum of the angles in a triangle: On the sphere the sum of the angles in a triangle is always strictly greater than 180 degrees.

## Why are there no parallel lines in Euclidean geometry?

Note that not having any parallel lines means that parallelograms do not exist. Recall that a parallelogram is a 4-gon that has the property that opposite sides are parallel. In Euclidean geometry this definition is equivalent to the definition that states that a parallelogram is a 4-gon where opposite angles are equal.

## Which is equivalent to a parallelogram in spherical geometry?

In Euclidean geometry this definition is equivalent to the definition that states that a parallelogram is a 4-gon where opposite angles are equal. In spherical geometry these two definitions are not equivalent. There are quadrilaterals of the second type on the sphere. Any two points can be joined by a straight line.