Answer:
15 cm
Step-by-step explanation:
Circumference of circle= 2πr, where r us the radius of the circle.
Given that the circumference of circle is 60πcm,
60π= 2πr
Divide by 2 on both sides,
15π= πr
Divide by π on both sides,
15= r
Thus, radius of circle= 15cm.
Answer:
y = 6x² -13x -5
Step-by-step explanation:
(1,-12) (2,-7) (5,80)
y = ax² + bx + c
-12 = a*1² + b*1 + c = a+b+c (1)
-7 = 4a + 2b + c (2)
80 = 25a + 5b + c (3)
(2)-(1): 3a + b = 5 (4)
(3)-(2): 21a + 3b = 87 (5)
(4)*3: 9a + 3b = 15 (6)
(5)-(6): 12a = 72 a = 6
(4) b = -13
(2) c = -5
Answer:
The rate at which the distance between them is changing at 2:00 p.m. is approximately 1.92 km/h
Step-by-step explanation:
At noon the location of Lan = 300 km north of Makenna
Lan's direction = South
Lan's speed = 60 km/h
Makenna's direction and speed = West at 75 km/h
The distance Lan has traveled at 2:00 PM = 2 h × 60 km/h = 120 km
The distance north between Lan and Makenna at 2:00 p.m = 300 km - 120 km = 180 km
The distance West Makenna has traveled at 2:00 p.m. = 2 h × 75 km/h = 150 km
Let 's' represent the distance between them, let 'y' represent the Lan's position north of Makenna at 2:00 p.m., and let 'x' represent Makenna's position west from Lan at 2:00 p.m.
By Pythagoras' theorem, we have;
s² = x² + y²
The distance between them at 2:00 p.m. s = √(180² + 150²) = 30·√61
ds²/dt = dx²/dt + dy²/dt
2·s·ds/dt = 2·x·dx/dt + 2·y·dy/dt
2×30·√61 × ds/dt = 2×150×75 + 2×180×(-60) = 900
ds/dt = 900/(2×30·√61) ≈ 1.92
The rate at which the distance between them is changing at 2:00 p.m. ds/dt ≈ 1.92 km/h