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Surface area of a triangular prism part 2
Hi guys, welcome to the part 2 in our journey in calculating in coming up with the total,
and complete entire surface area of this triangular prism. Now you may, recall and remember from
part 1, we calculate the front triangular phase, phrasal area of this triangular prism
that is right here, we work that out as 22.96 cm. and it is the same area as the back phase
over here in brown that triangular phase that is also 22.96cm, so we got two phases out
of the complete total of the five phases. Now we have three phases left we got to work
out here now remember all units are in centimeters, so the final answer were in centimeter squared
and we are looking for the answer of two decimal so let us take a look what is left the three
panels the three phases we got here they are the ones they envelope around here they are
the three rectangles when flattened out the rectangles across here . so let us take a
closer look at each of this rectangles. Now for the top one here, we know length is 26
cm, now this length across here this breth is also going to be seven across there because
we have 7 across there perfectly around the triangle. So we have here two little symbol
which represent or symbolize isosceles triangle which means this side and that side is both
7, and that, and that is 7, meaning that, this width and that width is also 7, so can
I just mark them in for you, now, we have 7 there and also 7 there, which means that
there is also 7 there. Lots of 7’s there. Now, the middle panel right here, this phase
here, that rectangle is actually different because the base of the triangle cross there
you will notice is 8, which means the base right in the middle is also 8, that is going
to be 8x 26 that will a little different to the other two let us now mark out, label the
area one, area two, area three so we can make this work out perfectly. So the top one over
here let us call that area 1 yeah, and the middle 1 across here area two, the bottom
one across here let us call that area three. Ok we got the three areas so let us work out
each 1, individually so let us start with area 1- it is quite simply, straight forward
all we need to do is multiply length times breth, so the first rectangle area one there
is 7 x26, let us do that. 7x26 is 182. Now let us go for area two; which is the middle
one there, remember that the base is a different. So that is going to be as you see the base is 8 x 26 and that is
going to give us a grand total of 208 cm. squared more unit of centimeter squared of
course and finally area three that is the bottom across there, that is the same as area
7x26 again, and again that is going to yield a 182 cm. squared. Ok, we have the three panels,
three rectangles calculated all we need to do is add those three to the first two triangle
phases right over there the front phase and the back phase all together we have five phases
let us add all of them up for the complete entire, total surface of this triangular prism,
so let us add them all up . So from the front phase there we have 22.96cm
and the back phase also is 22.96cm and then we have area 1 across there 182cm and the
middle base of bottom phase right over there, and one of the side here the area three is
also 182cm. let us just check we have five phases, 1,2,3,4,5 yes let us total that up
for completing entire total surface area of this triangular prism is the total of 617.92cm
squared.
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