Sine waves – trigonometry – math
Sine wave In order to save energy, many, many things in nature move in a kind of repeated pattern we call a sine wave: water waves, sound waves, light waves, [...]
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07, 2017
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07, 2017
Cosine – Trigonometry – Math
Right triangle and cosine What is a cosine? A cosine, like a sine, is a mathematical way of thinking about a kind of movement that happens in nature. A cosine is [...]
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07, 2017
What is a triangle? Simple geometry
This is an equilateral triangle. A triangle is any set of three points on a plane and the lines connecting those points to each other, as long as the three points aren't all on the [...]
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07, 2017
What is a trapezoid? Simple geometry
This is a trapezoid. A trapezoid is a kind of quadrilateral that has at least two sides that are parallel to each other. A parallelogram is a trapezoid that has two pairs of parallel [...]
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07, 2017
What is a square? Simple geometry
This is a square. The darker purple line is the perimeter of the square. A square is a flat shape, in one plane, defined by four points at the four corners. A square [...]
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07, 2017
Right triangle – Simple geometry
This is a right triangle, because one of the angles is a right angle. A right triangle is any triangle where one of the angles is exactly 90 degrees, or a right angle. You [...]
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07, 2017
Rectangle – area and perimeter
This is a rectangle. A rectangle is a flat shape, in one plane. It's defined by four points at the four corners. A rectangle has two sides of equal length opposite each other, [...]
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07, 2017
What is a quadrilateral? Squares and rectangles
This is a quadrilateral. A quadrilateral is a flat shape, in one plane, defined by four points at the four corners. A quadrilateral has four sides. The sides can be of any length. [...]
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07, 2017
Perpendicular lines – Simple geometry
Perpendicular lines Two lines are perpendicular if they cross at right angles. You can test this by extending the lines until they cross (if they do not cross then they are parallel). Where the [...]
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07, 2017
What is a cube? Simple geometry
Do you know how to do a Rubik's cube? A cube is a square moved through space, so it gets thicker. All cubes have six sides - the top, the bottom, and [...]
