randomQuadAngles.trapezoid() randRange( 0, 3 ) ANSWER_POS % 2 == 0 ? ( ANSWER_POS + 3 ) % 4 : ( ANSWER_POS + 1 ) % 4 function(){ var a = [ "", "","" ,"" ]; a[ ANSWER_POS ] = "x"; a[ SHOWN_POS ] = ANGLES[ SHOWN_POS ] + "^{\\circ}"; return a; }()
What is the value of the angle marked with "x" ?
init({ range: [ [-1, 12 ], [ -8, -1 ] ] }) var q = new Quadrilateral( [ 3.5, -7 ], ANGLES, randRange(0, 1 ) + 0.5, "", 3 ); q.boxOut( [ [ [ 0, -10 ], [ 0, 10 ] ] ], [ 0.7, 0 ] ); q.boxOut( [ [ [ 11, -10 ], [ 11, 10 ] ] ], [ -0.7, 0 ] ); q.draw(); q.labels = { "angles" : ANG_LABELS, "sides" : jQuery.map( jQuery.map( q.sides, lineLength ), function( x ){ return x.toFixed( 1 ); } ) }; q.drawLabels();

This figure is a trapezoid.

The angles of a trapezoid side are supplementary.

`ANGLES[ SHOWN_POS ] + x = 180`

`x = 180 - ANGLES[ SHOWN_POS ]`

`x = ANGLES[ ANSWER_POS ]`

randomQuadAngles.isoscelesTrapezoid() ANSWER_POS % 2 == 0 ? ( ANSWER_POS + 1 ) : ( ANSWER_POS - 1 )

This figure is an isosceles trapezoid.

The angles of bases of an isosceles trapezoid are equal.

Therefore, the angle x is also `ANGLES[ SHOWN_POS ]`

randomQuadAngles.parallelogram() ( ANSWER_POS + 2 ) % 4

This quadrilateral is a parallelogram.

Opposite angles of a parallelogram are equal.

Therefore, the angle x is also `ANGLES[ SHOWN_POS ]`

randomQuadAngles.parallelogram() ANSWER_POS % 2 == 0 ? ( ANSWER_POS + 1 ) : ( ANSWER_POS - 1 )

This quadrilateral is a parallelogram.

Adjacent angles of a parallelogram are supplementary.

`ANGLES[ SHOWN_POS ] + x = 180`

`x = 180 - ANGLES[ SHOWN_POS ]`

`x = ANGLES[ ANSWER_POS ]`

init({ range: [ [-1, 13 ], [ -8, -1 ] ] }) var q = new Quadrilateral( [ 3.5, -7 ], ANGLES, 1, "", 3 ); q.boxOut( [ [ [ 0, -10 ], [ 0, 10 ] ] ], [ 0.7, 0 ] ); q.boxOut( [ [ [ 12, -10 ], [ 12, 10 ] ] ], [ -0.7, 0 ] ); q.draw(); q.labels = { "angles" : ANG_LABELS, "sides" : jQuery.map( jQuery.map( q.sides, lineLength ), function( x ){ return x.toFixed( 1 ); } ) }; q.drawLabels();

This quadrilateral is a rhombus, because it has all sides equal.

Opposite angles of a rhombus are equal.

Therefore, the angle x is also `ANGLES[ SHOWN_POS ]`

randomQuadAngles.rhombus() ANSWER_POS % 2 == 0 ? ( ANSWER_POS + 1 ) : ( ANSWER_POS - 1 )

This quadrilateral is a rhombus, because it has all sides equal.

Adjacent angles of a rhombus are supplementary.

`ANGLES[ SHOWN_POS ] + x = 180`

`x = 180 - ANGLES[ SHOWN_POS ]`

`x = ANGLES[ ANSWER_POS ]`

randomQuadAngles.kite() randFromArray( [ 1, 3 ] ) ( ANSWER_POS + 2 ) % 4

This quadrilateral is a kite, because it has two pairs of adjacent sides equal.

Angles between the non-equal sides of a kite are equal.

Therefore, the angle x is also `ANGLES[ SHOWN_POS ]`