Area of parallelogram

$val7
($val16,$val17) , ($val18,$val19) , ($val20,$val21) , ($val22,$val23).

Area of pentagon

$val7
= ($val11,$val12), = ($val34), = ($val36), = ($val37), = ($val35).

Area of quadrilateral

xrange -15,15 yrange -15,15 arrow -15,0,15,0,10,grey arrow 0,-15,0,15,10,grey linewidth 2 polygon red,$val12,$val13,$val14,$val15,$val16,$val17,$val18,$val19 linewidth 4 points blue,$val12,$val13,$val14,$val15,$val16,$val17,$val18,$val19
$val7
= ($val12,$val13), = ($val30), = ($val16,$val17), = ($val31).

Area of triangle

$val7
($val16,$val17), ($val18,$val19), ($val20,$val21).

Angle

$val7
, , .
$val8

Combination

$(val7[1])
, .
$(val7[2])
.

Combination 3 vectors

$(val7[1])
, , .
$(val7[2])
.

Find combination

$(val7[1;])
, .
$(val7[2;]) $(val7[3;]):
.

Given scalar products

$(val7[1])
, .
$(val7[2]):
, .
$val8

Vertex of parallelogram

$val7
, , .
$val8 .

Linear relation

$(val7[1;]):
.
$(val7[2;])
,
$(val7[3;])