Answer:
a₁ = -5, d = 7, a₂ = 2, a₃ = 9, a₄ = 16
equation of sequence:
Step-by-step explanation:
a₁ + a₂ + a₃ = 6
a₁ + a₁ + d + a₁ + 2d = 6
3a₁ + 3d = 6
a₁ + d= 2 ⇒ a₁ = 2 - d
a₄ = 16
a₁ + 3d = 16
2 - r + 3d = 16
2d = 14
d = 7
a₁ = 2-7 = -5
a₁ = -5, d = 7 ⇒ a₂ = -5+7 = 2, a₃ = 2+7 = 9, a₄ = 9+7 = 16
equation of arithmetic sequence:
Answer:
81.75 ft²
Step-by-step explanation:
The area (A) of a trapezoid is calculated using the formula
A = h (a + b)
where a, b are the parallel bases and h is the perpendicular height
Calculate h using the right triangle and the sine ratio
sin30° = =
Multiply both sides by 10
10 × sin30° = h, thus
h = 5
a = 12 and b = 8.7 + 12 = 20.7, hence
A = × 5 × (12 + 20.7)
= 0.5 × 5 ×32.7
= 81.75 ft²