"Area and Perimeter of Triangle
'<hr /><div style="max-width:110mm;"><img style="height:55pt;" class="side" alt="triangle.png" src="https://calcpad.eu/media/math/area/triangle.png"></div>
'Side lengths
a = ?','b = ?','c = ?
'<!--
#if (a + b > c)*(b + c > a)*(c + a > b)
	'<-->
	'Perimeter 
	P = a + b + c
	'Area (Heron formula)
	'Semiperimeter -'p = 0.5*P
	A = sqr(p*(p - a)*(p - b)*(p - c))
	'<!--
#else
	'<-->
	'The sum of the lengths of each two sides must be greater than the third side.
	'<!--
#end if
'<-->5	4	3