Check the picture below.
notice that the triangle ADH, since the segment AL is an angle bisector, meaning it cuts the angle A in two equal halves, then the triangle ADH is only using half of A.
Step-by-step explanation:
look at the picture !
she has to paint actually 6 rectangles :
the 3 tops of the 3 stairs.
and the 3 vertical front boards (the front of each step of the stairs).
what is the area of these rectangles ? summing up all 6 - that is the surface area to be painted.
each top rectangle is clearly
82×19 (19 cm deep) = 1558 cm²
each front board is
82×12 (12 cm high) = 984 cm²
so, in total we have
3×1558 + 3×984 = 4674 + 2952 = 7626 cm²
as surface area to be painted.
Perimeter = 2(length + width)
p = 2(10'5" + 9'8")
p = 2(19'13")
p = 38'26"
26" = 2'4"
So...
38' + 2'4" = 40' 4" for the perim,eter
