The surface area is the area of the outside of a 3D shape for example, let’s say you have a cube, a cube has 6 sides, so you have to find the area of each side and then add it up, since it’s a cube you would technically have to find the area of one side and then just multiply it by 6, that would be the easiest way to do it
Hope I helped!
Nearest 10 is according to the last digit.
if the digit is >5, it +1 to the tenth digit. If it's <5, it will be reduced to 0.
for your case, 392, 2 < 5, therefore rounded up to nearest tenth is 390.
Answer:
21) 12 cm
22) 5.9 cm
Step-by-step explanation:
21) The base is 10, and if the other two sides are congruent and the perimeter is 36, we can figure out with simple algebra that the sides are 13 cm long.
Half of 10 is 5, so we can use the pythagorean theorem.
5^2+x^2=13^2
Rearranging the variables we have 169-25=x^2
144=x^2
x can be plus or minus 12, but since negative length is impossible we find that x is positive 12 cm.
22) We want to use sine, because we have opposite and hypotenuse. A simple and easy way to memorize this is the SohCahToa method. If we have opposite (O) and hypotenuse (H) we have OH. Soh has the letters O and H, and the S means we should use sine.
sine 36=a/10
Plug this into a calculator or desmos scientific calculator to get a=5.9
Number two is proportional just do Y over X y/x meaning divided all the y’s over the x’s so 25 divided by 5 30 divided by 6 35/7 40/8 they all equal 5 so it’s proportional
number three isn’t proportional when you do y/x they all come out differently so you do y2-y1 over x2-x1 16-4/4-2 16-4=12 4-2=2 then you divided 12/2 that equals 6 you do that again but with the next numbers but they don’t equal so it’s no equation no constant
