that first pic, with triangle on it. ahaha i remember those, ive always been different from everyone else. since i never bothered to use any formulas for them or do any math, i always took logical and simple way.
by measuring it :) haha
if you need to calculate the size of this shape, then simply make another one to form a 4 tip shape (dunno how its called) and count the squares in it or just do side X side, then divide by 2 and you get the answer.
i always used squared paper for math and i always counted the squares, teachers were always angry cuz i did it other way .. FFS in real life it doesnt matter HOW you get the answer, just as long as you get it !