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math math-format graphie graphie-helpers
Multiply Complex Numbers in Polar Form
multiplying_complex_number_polar_forms
custom
13552
24 randFromArray( [ true, false ] )
randRange(1, 10) randRange(1, 10) A_RADIUS * B_RADIUS
"{" + A_RADIUS + "}" randRange(1, DENOMINATOR - 1 ) A_ANGLE_NUMERATOR * PI * 2 / DENOMINATOR "{" + piFraction(A_ANGLE, true) + "}" "{" + polarForm(A_RADIUS, A_ANGLE, USE_EULER_FORM) + "}" cos( A_ANGLE ) * A_RADIUS sin( A_ANGLE ) * A_RADIUS "\\red{" + B_RADIUS + "}" randRange(1, DENOMINATOR - 1 ) B_ANGLE_NUMERATOR * PI * 2 / DENOMINATOR "\\red{" + piFraction(B_ANGLE, true) + "}" "\\red{" + polarForm(B_RADIUS, B_ANGLE, USE_EULER_FORM) + "}" cos( B_ANGLE ) * B_RADIUS sin( B_ANGLE ) * B_RADIUS "\\blue{" + ANSWER_RADIUS + "}" ( A_ANGLE_NUMERATOR + B_ANGLE_NUMERATOR ) % DENOMINATOR ANSWER_ANGLE_NUMERATOR * PI * 2 / DENOMINATOR "\\blue{" + piFraction(ANSWER_ANGLE, true) + "}" cos( ANSWER_ANGLE ) * ANSWER_RADIUS sin( ANSWER_ANGLE ) * ANSWER_RADIUS "{" + piFraction((A_ANGLE_NUMERATOR + B_ANGLE_NUMERATOR) * PI * 2 / DENOMINATOR, true) + "}"

Multiply the following complex numbers:

{\color{blue}z} = v \cdot {\color{red}w} = \left(A_REP\right) \cdot \left(B_REP\right)

graphInit({ range: [ [ -10, 10 ], [ -10 ,10 ] ], scale: 20, tickStep: 1, axisArrows: "->" }); drawComplexChart( 10, DENOMINATOR ); label( [A_REAL, A_IMAG], "\\color{black} v", "left" ); circle( [A_REAL, A_IMAG], 1 / 4, { fill: KhanUtil.BLACK, stroke: "none" }); label( [B_REAL, B_IMAG], "\\color{red} w", "right" ); circle( [B_REAL, B_IMAG], 1 / 4, { fill: KhanUtil.RED, stroke: "none" }); graph.currComplexPolar = new ComplexPolarForm( DENOMINATOR, 10 ); graph.currComplexPolar.color = BLUE; redrawComplexPolarForm();
{\color{blue}z} =

1

[ graph.currComplexPolar.getAngleNumerator(), graph.currComplexPolar.getRadius() ]
var angle = guess[0]; var radius = guess[1]; if (angle === 0 && radius === 1) { return ""; } return angle === ANSWER_ANGLE_NUMERATOR && radius === ANSWER_RADIUS;
redrawComplexPolarForm(guess[0], guess[1]);
redrawComplexPolarForm(guess[0], guess[1]);

The multiplication of two polar forms is given by multiplying the absolute values und add the angles.

The first number, v = A_REP, has angle A_ANGLE_REP and absolute value A_RADIUS_REP.

The second number, {\red w} = B_REP, has angle B_ANGLE_REP and absolute angle B_RADIUS_REP.

The absolute value of the result is thus A_RADIUS_REP \cdot B_RADIUS_REP = ANSWER_RADIUS_REP.

The sum of the angles is A_ANGLE_REP + B_ANGLE_REP = INTERMEDIATE_ANGLE_REP.

The angle INTERMEDIATE_ANGLE_REP ist grösser als 2 \pi. Eine komplexe Zahl kehrt zum Ausgangspunkt zurück, wenn der Winkel um 2 \pi erhöht wird.

Thus, the angle here is INTERMEDIATE_ANGLE_REP - 2 \pi = ANSWER_ANGLE_REP to be set to.

The sum of the angles is A_ANGLE_REP + B_ANGLE_REP = ANSWER_ANGLE_REP.