Answer:The general equation of a sphere is: (x - a)² + (y - b)² + (z - c)² = r², where (a, b, c) represents the center of the sphere, r represents the radius, and x, y, and z are the coordinates of the points on the surface of the sphere.

Step-by-step explanation:

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3 years ago

A racing shell, which is a boat a crew team rows, moves 20 km/h in still water. During practice, the team rows 36 km against the

saveliy_v [14]

Answer:

2 km/h

Step-by-step explanation:

Let x represent the speed of the river current, t₁ be the time spent rowing against the current and t₂ be the time spent rowing with the current.

Since the speed of the still water = 20 km/h.

The speed of rowing against the current = (20 - x)

The speed of rowing with the current = (20 + x)

We know that velocity = distance / time. Hence time = distance / velocity

t₁ = 36 / (20 - x)

t₂ = 22 / (20 + x)

but t₁ + t₂ = 3 hours

Therefore:

3 = 36 / (20 - x) + 22 / (20 + x)

multiply through by 400 - x²

3(400 - x²) = 36(20 + x) + 22(20 - x)

1200 - 3x² = 720 + 36x + 440 - 22x

3x² + 14x -40 = 0

This gives x = -6.7 or x = 2

x cannot be negative therefore x = 2 km/h

The speed of the river current is 2 km/h

4 0

3 years ago

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