A. 386.9 ft2
B. 593.8 ft2
C. 639.4 ft2
D. 1,053.2 ft2
Answer:
The correct option is B.
Step-by-step explanation:
The area of pyramid is the sum of area of rectangular base and 4 triangular sides. Two triangle have base 18 ft and height 14.1 ft. Other two have base 10 ft and height 16 ft.
The area of rectangle is
Length of the base is 18ft and width is 10ft.
The area of a triangle is
The area of triangle with base 18 ft and height 14.1 ft is
The area of triangle with base 10 ft and height 16 ft is
The total surface area of the rectangular pyramid is
The surface area of the rectangular pyramid is 593.8 ft². Therefore the correct option is B.
Answer:
it is B
Step-by-step explanation:
Let the first term, common difference and number of terms of an AP are a, d and n respectively.
Given that, 9th term of an AP, T9 = 0 [∵ nth term of an AP, Tn = a + (n-1)d]
⇒ a + (9-1)d = 0
⇒ a + 8d = 0 ⇒ a = -8d ...(i)
Now, its 19th term , T19 = a + (19-1)d
= - 8d + 18d [from Eq.(i)]
= 10d ...(ii)
and its 29th term, T29 = a+(29-1)d
= -8d + 28d [from Eq.(i)]
= 20d = 2 × T19
Hence, its 29th term is twice its 19th term
Answer:
Proved below.
Step-by-step explanation:
a9 = a1 + 8d = 0 where a1 = first term and d = common difference.
we need to prove that
a1 + 28d = 2(a1 + 18d
simplifying:-
a1 + 36d - 28d = 0
a1 + 8d = 0 which is what we are given.
Therefore the proposition is true.