Contemporary geometry has many sub fields

• Euclidean geometry is geometry in its classical sense. The mandatory educational curriculum of the majority of nations includes the study of points, lines, planes, angles, triangles, congruence, similarity, solid figures, circles, and analytic geometry.Euclidean geometry also has applications in computer science, crystallography, and various branches of modern mathematics.

• Differential geometry uses techniques of calculus and linear algebra to study problems in geometry. It has applications in physics, including in general relativity.

• Topology is the field concerned with the properties of geometric objects that are unchanged by continuous mappings. In practice, this often means dealing with large-scale properties of spaces, such as connectedness and compactness.

• Convex geometry investigates convex shapes in the Euclidean space and its more abstract analogues, often using techniques of real analysis. It has close connections to convex analysis, optimization and functional analysis and important applications in number theory.

• Algebraic geometry studies geometry through the use of multivariate polynomials and other algebraic techniques. It has applications in many areas, including cryptography and string theory.

• Discrete geometry is concerned mainly with questions of relative position of simple geometric objects, such as points, lines and circles. It shares many methods and principles with combinatorics.

Geometry

Geometry (from the Ancient Greek: γεωμετρία; geo- “earth”, -metron “measurement”) 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.

Geometry arose independently in a number of early cultures as a practical way for dealing with lengths, areas, and volumes. Geometry began to see elements of formal mathematical science emerging in the West as early as the 6th century BC. By the 3rd century BC, geometry was put into an axiomatic form by Euclid, whose treatment, Euclid’s Elements, set a standard for many centuries to follow. Geometry arose independently in India, with texts providing rules for geometric constructions appearing as early as the 3rd century BC. Islamic scientists preserved Greek ideas and expanded on them during the Middle Ages. By the early 17th century, geometry had been put on a solid analytic footing by mathematicians such as René Descartes and Pierre de Fermat. Since then, and into modern times, geometry has expanded into non-Euclidean geometry and manifolds, describing spaces that lie beyond the normal range of human experience.

While geometry has evolved significantly throughout the years, there are some general concepts that are more or less fundamental to geometry. These include the concepts of points, lines, planes, surfaces, angles, and curves, as well as the more advanced notions of manifolds and topology or metric.

Algebra

Algebra (from Arabic “al-jabr” meaning “reunion of broken parts”) is one of the broad parts of mathematics, together with number theory, geometry and analysis. In its most general form, algebra is the study of mathematical symbols and the rules for manipulating these symbols; it is a unifying thread of almost all of mathematics. As such, it includes everything from elementary equation solving to the study of abstractions such as groups, rings, and fields. The more basic parts of algebra are called elementary algebra, the more abstract parts are called abstract algebra or modern algebra. Elementary algebra is generally considered to be essential for any study of mathematics, science, or engineering, as well as such applications as medicine and economics. Abstract algebra is a major area in advanced mathematics, studied primarily by professional mathematicians.

The word algebra is also used in certain specialized ways. A special kind of mathematical object in abstract algebra is called an “algebra”, and the word is used, for example, in the phrases linear algebra and algebraic topology.

A mathematician who does research in algebra is called an algebraist.

Pythagoras

Pythagoras’ theorem states that for all right-angled triangles, ‘The square on the hypotenuse is equal to the sum of the squares on the other two sides’. The hypotenuse is the longest side and it’s always opposite the right angle.

In this triangle  a2 = b2 + c2 and angle A is a right angle.

Pythagoras’ theorem only works for right-angled triangles, so you can use it to test whether a triangle has a right angle or not.

In the triangle above, if  a2 < b2 + c2  the angle A is acute.

In the triangle above, if  a2 > b2 + cthe angle A is obtuse.

Mathematics

Mathematics (from Greek μάθημα máthēma, “knowledge, study, learning”) is the study of topics such as quantity (numbers), structure, space, and change. There is a range of views among mathematicians and philosophers as to the exact scope and definition of mathematics.

Mathematicians seek out patterns and use them to formulate new conjectures. Mathematicians resolve the truth or falsity of conjectures by mathematical proof. When mathematical structures are good models of real phenomena, then mathematical reasoning can provide insight or predictions about nature. Through the use of abstraction and logic, mathematics developed from counting, calculation, measurement, and the systematic study of the shapes and motions of physical objects. Practical mathematics has been a human activity from as far back as written records exist. The research required to solve mathematical problems can take years or even centuries of sustained inquiry.

Addition of similar digit

Traditionally this is very time consuming to calculate the Addition of Similar Digit Number, and it create confusion at that moment in speed. So don’t worry here we have given you Quick shortcut tricks to do quickly calculation. Sometimes we face this type of problems in our exam or daily routine.

Example:   7 + 77 + 777 + 7777 + 77777 = ?

Shortcut Tricks

Step 1: Take 8 common and Replace all 7 with 1.
i.e, 7(1 + 11 + 111 + 1111 + 11111)

Step 2: Count number of digits in each number,
i.e, 1=1(digit), 11=2(digit), 111=3(digit), 1111=4(digit), 11111=5(digit),
and write down all digits together that is 12345.

Step 3: Multiply 7 x 12345 = 86415.
The final result is 86415.