Answer:
480
Step-by-step explanation:
Sn = n÷2 × (2a + (n-1)d)
n = 20 a = -14 d = 4
S20 = 10 × (-28 + 19 × 4) = 480
Answer:
BD = 12 :)
Step-by-step explanation:
Alright, we'll need the Pythagorean theorem for this!
So, the length of AC is 10. That means the lengths of AD and DC are both half of that, which is 5 :)
DC = 5
We already know that BC = 13, so we can plug in these values into the pythagorean theorem for the right triangle BDC:
BD^2 + DC^2 = BC^2
BD^2 + 5^2 = 13^2
BD^2 + 25 = 169
BD^2 = 169 - 25 = 144
BD = √144 = 12 :)
Volume = length x width x height
Volume = 1 x 10 x 20.5
Volume = 205 m^3
Answer: B
Step-by-step explanation:
5 because 25 divided by 5 is 5
