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Ptolemy's theorem states that the sum of the products of the lengths of opposite sides is equal to the product of the lengths of the diagonals. When those side-lengths are expressed in terms of the sin and cos values shown in the figure above, this yields the angle sum trigonometric identity for sine: sin(α + β) = sin α cos β + cos α sin β.
The term "isometric" comes from the Greek for "equal measure", reflecting that the scale along each axis of the projection is the same (unlike some other forms of graphical projection). An isometric view of an object can be obtained by choosing the viewing direction such that the angles between the projections of the x , y , and z axes are all ...
The plane z = 0 runs through the center of the sphere; the "equator" is the intersection of the sphere with this plane. For any point P on M, there is a unique line through N and P, and this line intersects the plane z = 0 in exactly one point P ′, known as the stereographic projection of P onto the plane.
Equal length; Equal length and parallel; Equal length and perpendicular (say, for ideal targeting of at least one) Equal to lengths of a specified ratio; others. In the examples, the general solution for each desired characteristic solution is a cone, each element of which produces one of an infinite number of solution views.
The theorem may also be proven using trigonometry: Let O = (0, 0), A = (−1, 0), and C = (1, 0). Then B is a point on the unit circle (cos θ, sin θ). We will show that ABC forms a right angle by proving that AB and BC are perpendicular — that is, the product of their slopes is equal to −1. We calculate the slopes for AB and BC:
The figures are said to be perspective from this axis. The point at which the lines joining the corresponding vertices of the perspective figures intersect is called the center of perspectivity, perspective center, homology center, pole, or archaically perspector. The figures are said to be perspective from this center. [1]
The vanishing point may also be referred to as the "direction point", as lines having the same directional vector, say D, will have the same vanishing point. Mathematically, let q ≡ ( x , y , f ) be a point lying on the image plane, where f is the focal length (of the camera associated with the image), and let v q ≡ ( x / h , y ...
In mathematics, sine and cosine are trigonometric functions of an angle.The sine and cosine of an acute angle are defined in the context of a right triangle: for the specified angle, its sine is the ratio of the length of the side that is opposite that angle to the length of the longest side of the triangle (the hypotenuse), and the cosine is the ratio of the length of the adjacent leg to that ...