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A horn antenna or microwave horn is an antenna that consists of a flaring metal waveguide shaped like a horn to direct radio waves in a beam. Horns are ... more

The formula for the calculation of the angular velocity of a wind turbine rotor. The definition is according to the IEC 61400-2. ... more

Using the Pythagorean theorem, for 3 different screen resolutions:

Using the Diagonal Resolution from the previous formula we calculate the PPI for 3 corresponding screen sizes :

**Results:**

**10.1** inch tablet screen of resolution **1024×600** : **117.5PPI****21.5** inch PC monitor of **1080p** resolution : **102.46PPI****27** inch PC monitor of **1440p** resolution : **108.78PPI**

The general equation for a circle with a center not necessary at the pole, gives the length of the radius of the circle.

The polar coordinate system
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In mathematics, the polar coordinate system is a two-dimensional coordinate system in which each point on a plane is determined by a distance from a fixed ... more

A spheroid, or ellipsoid of revolution is a quadric surface obtained by rotating an ellipse about one of its principal axes; in other words, an ellipsoid ... more

A spheroid, or ellipsoid of revolution is a quadric surface obtained by rotating an ellipse about one of its principal axes; in other words, an ellipsoid ... more

Precession is a change in the orientation of the rotational axis of a rotating body. In an appropriate reference frame it can be defined as a change in the ... more

Precession is a change in the orientation of the rotational axis of a rotating body. In an appropriate reference frame it can be defined as a change in the ... more

Moment of inertia is the mass property of a rigid body that determines the torque needed for a desired angular acceleration about an axis of rotation. ... more

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PPI can be calculated from knowing the diagonal size of the screen in inches and the resolution in pixels (width and height). This can be done in two steps