randRange( 20, 160 ) shuffle( randFromArray( [ [ 2, 4 ], [ 3, 5 ] ] ) ) KNOWN_INDEX % 2 === 0 ? ANCHOR : 180 - ANCHOR $._("pink angle") $._("orange angle")

If we know that the blue angle is MEASURE degrees, what is the measure of the orange angle?

MEASURE \Large{^\circ}
init({ range: [ [ -1, 5 ], [-1, 1] ] }); graph.pl = new ParallelLines( 0, 0, 4, 0, 0 ); graph.pl.draw(); graph.pl.drawTransverse( ANCHOR ); graph.pl.drawAngle( KNOWN_INDEX, true ); graph.pl.drawAngle( UNKNOWN_INDEX, false, "#FFA500" );

What is the measure of the pink angle?

graph.pl.drawAngle( KNOWN_INDEX + 1, false, "#FF00AF" );

The pink and blue angles add up to 180 because they are adjacent and form a straight line.

\color{#FF00AF}{\text{PINK_ANGLE}}= 180^{\circ} - \color{#6495ED}{MEASURE^{\circ}} = \color{#FF00AF}{180 - MEASURE^{\circ}}

graph.pl.drawAngle( KNOWN_INDEX + 1, true, "#FF00AF" );

The pink and orange angles also add up to 180 because they are adjacent and form a straight line too.

\color{#FFAF00}{\text{ORANGE_ANGLE}}= 180^{\circ} - \color{#FF00AF}{180 - MEASURE^{\circ}} = \color{#FFAF00}{MEASURE^{\circ}}

graph.pl.drawAngle( UNKNOWN_INDEX, true, "#FFA500" );