Answer:
Step-by-step explanation:
r(t) = (7 cost + 7t sin t)i + (7 sin t - 7t cos t)j







Using eq (1) and (2)

Answer:
$90
Step-by-step explanation:
8 + 4 = 12
12 x 3 (3 feet for each inch) = 36
36 x 2.50 (cost per square foot) = $90
Answer:
b = 10
Step-by-step explanation:
The area (A) of a triangle is calculated as
A =
bh ( b is the base and h the height )
Here h = 3x + 15 and A = 15x + 75, thus
× b × (3x + 15) = 15x + 75
Multiply both sides by 2 to clear the fraction
b(3x + 15) = 30x + 150
Divide both sides by (3x + 15)
b =
← factor numerator and denominator
=
← cancel the factor (x + 5) on numerator/denominator
= 
= 10