Property	Value
Hex Value	`$1D`
Categories	Angle Catalog > P
Localizations	FR: `P►Rx(`

`P►Rx(`

Overview

Returns X, given polar coordinates r and θ or a list of polar coordinates.

Availability: Token available everywhere.

Syntax

P►Rx(r,θ)

Arguments

Name	Type	Optional
r
θ

Location

2nd, angle, ANGLE, 7:P, Rx(

Description

P►Rx( (polar►rectangular x-coordinate) calculates the x-coordinate of a polar point. Polar coordinates are of the form (r,θ), where θ is the counterclockwise angle made with the positive x-axis, and r is the distance away from the origin (the point (0,0)). The conversion identity x=r*cos(θ) is used to calculate P►Rx(.

The value returned depends on whether the calculator is in radian or degree mode. A full rotation around a circle is 2π radians, which is equal to 360°. The conversion from radians to degrees is angle180/π and from degrees to radians is angleπ/180. The P►Rx( command also accepts a list of points.

P►Rx(5,π/4)
    3.535533906
5*cos(π/4)
    3.535533906
P►Rx({1,2},{π/4,π/3})
    {.7071067812 1}

Advanced Uses

You can bypass the mode setting by using the ° (degree) and ^ʳ (radian) symbols. This next command will return the same values no matter if your calculator is in degrees or radians:

P►Rx(1,{π/4^^r,60°})
    {.7071067812 .5}

Optimization

In most cases P►Rx(r,θ) can be replaced by r*cos(θ) to save a byte:

:P►Rx(5,π/12)
can be
:5cos(π/12)

Conversely, complicated expressions multiplied by a cosine factor can be simplified by using P►Rx(r,θ) instead.

:(A+BX)cos(π/5)
can be
:P►Rx(A+BX,π/5)

Error Conditions

ERR:DIM MISMATCH is thrown if two list arguments have different dimensions.
ERR:DATA TYPE is thrown if you input a complex argument.

Source: parts of this page were written by the following TI|BD contributors: CloudVariable, DarkerLine, GoVegan, simplethinker, thornahawk.

History

Calculator	OS Version	Description
TI-82	1.0	Added

Authors: Adrien Bertrand

P►Rx(