## Arccosine

Select your language EnglishSpanish The arccosine (notation: arccos or cos-1) is the inverse function of the cosine. That is: As the arcsine and sine are inverse functions, their composition is the identity. That is:...

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## Mathematical Way Blog

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Double-Angle Formulas

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Perpendicular Bisector of a Triangle

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Altitude of a Triangle

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Perimeter of a triangle

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Scalene Triangle

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Similar triangles

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*"As for everything else, so for mathematical theory: beauty can be perceived but not explained."* - **ARTHUR CAYLEY**

Select your language EnglishSpanish Let α be an angle. The double-angle (2α) trigonometric ratios can be expressed as a function of the trigonometric ratios of the angle α, that is, the double-angle formulas: Double-Angle...

Select your language EnglishSpanish The perpendicular bisector of a segment is a line perpendicular to the segment that passes through its midpoint. It has the property that each of its points is equidistant from...

Select your language EnglishSpanish The altitude of a triangle, or height, is a line from a vertex to the opposite side, that is perpendicular to that side. It can also be understood as the...

Select your language EnglishSpanish The perimeter of a triangle is the sum of its three sides. The formula for the perimeter of a triangle depends on the type of triangle. But there is a...

Select your language EnglishSpanish A scalene triangle is a triangle in which all three sides have different lengths and all angles are diferent too. This type of triangle can be a right triangle (one...

Select your language EnglishSpanish In Euclidean geometry, two objects are similar if they are the same shape, regardless of their size. Two triangles are similar if, and only if, their angles are congruent (equal)...