Okay for both of these questions we need to know that the formula for surface area for triangles is 1/2base x height
and surface area for rectangles is length x width
okay here we g
#2
first lets find the surface area of all of the rectangles on the 3d picture and so far i see 3 rectangular sides
side 1: 1cm x 1.2cm = 1.2cm²
side 2: 1cm x 1.2cm = 1.2cm²
side 3: 1.2cm x 1.2cm = 1.44cm²
lets set this aside for now
now for our triangles:)
now im going to do this particular triangle differently
im actually going to find the surface area of half of 1 triangle and then multiply that by 4 so remember 1/2 base times height for triangles
and since im finding half of the triangle lets divide the base in half and put that in our equation
base of triangle:1.2cm divide!! by 2 now
1.2 ÷ 2 = 0.6
great lets add it into our equation:)
triangle 1: 1/2(0.6) x (0.8)
first lets solve what 1/2 times 0.6 is
1/2 x 0.6 = 0.3
now we can continue solving 0.3 times 0.8
0.3 x 0.8 = 0.24
so our answer for half of a triangle is 0.24cm!
but since we also have the other half and also the other two halfs of the other side of the 3d shape lets make things easier and just multiply our answer by 4
0.24 x 4 = 0.96cm²
we arent finished yet! lets add up our surface area all together including our 3 rectangular sides.
sooo
0.96 + 1.2 +1.2 + 1.44 = 4.8
so our answer for number 2 i 4.8cm²
next...
#3 so considering our knowledge from our last question you might already know that in order to find the surface area we need to use the formula length times width and for triangles the formula for that is 1/2 base times height. But remember this only works on right angled triangles that have 90 degrees. Thats why in our last question we had to divide it in half in order to make it a right angled triangle. LUCKILY in this question they already gave us a right angled triangle. but lets find the the area of the rectangles.
i see only 3 so enough talking and lets solve.
side 1: 10cm x 11cm = 110cm²
side 2: 11cm x 12cm = 132cm²
side 3: 11cm x 15.6cm = 171.6cm²
lets set this aside for now and take care of our triangles.
so we know our formula is
triangle area = 1/2(base) x (height)
so lets plug in what we know from our picture
1/2(12) x (10)
1/2 x 12 is 6 so now lets plug that in
6 x 10 = 60
so our surface area for 1 triangle is 60cm²
but we have two triangles do lets multiply that by 2
60 x 2 = 120cm²
so we have all of our surface area measurement now we can add them all up
120 + 110 + 132 + 171.6 = 533.6
so your surface area for number 2 is 533.6cm²
hope this makes sense and please
MARK ME BRAINLIEST!!
thxx:)
