B(cone)=B(pyramid)=r²π
V(pyramid)=1/3 * B * H = 1/3 * r² π * 3 r ( 3 will cancel out )= r³ π
Answer: r³ π
First term ,a=4 , common difference =4-7=-3, n =50
sum of first 50terms= (50/2)[2×4+(50-1)(-3)]
=25×[8+49]×-3
=25×57×-3
=25× -171
= -42925
derivation of the formula for the sum of n terms
Progression, S
S=a1+a2+a3+a4+...+an
S=a1+(a1+d)+(a1+2d)+(a1+3d)+...+[a1+(n−1)d] → Equation (1)
S=an+an−1+an−2+an−3+...+a1
S=an+(an−d)+(an−2d)+(an−3d)+...+[an−(n−1)d] → Equation (2)
Add Equations (1) and (2)
2S=(a1+an)+(a1+an)+(a1+an)+(a1+an)+...+(a1+an)
2S=n(a1+an)
S=n/2(a1+an)
Substitute an = a1 + (n - 1)d to the above equation, we have
S=n/2{a1+[a1+(n−1)d]}
S=n/2[2a1+(n−1)d]
Answer:
a. x = 14
b. Perimeter = 77
Step-by-step explanation:
a. Based on the Triangle Proportionality Theorem:
Cross multiply
Add 2 to both sides
Divide both sides by 2
x = 14
b. Perimeter of ∆QRS = RQ + QS + RS = (2x - 2) + 13 + 17 + (21 - 7) + 7
Plug in the value of x
= (2(14) - 2) + 13 + 17 + 14 + 7
= 26 + 13 + 17 + 14 + 7
= 77
Answer: B
Step-by-step explanation:
A = 0/360 ×π×r^2
=135/360×π×11×11
=142.55 yd^2
Answer:
133
Step-by-step explanation:
$3500 - $1500 = $2000
2000/1500 ×100
=1.33 × 100
=133%
