Evaluate the expression when a=-6 and c= 2 . a-4c
2 answers:
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One complete revolution of the minute hand sweeps a central angle of 360° which is equivalent to 60 minutes.
That is, the minute hand creates
(360°/(60 min) = 6 degrees/min.
From 3:35 to 3:55 is 20 minutes.
It sweeps a central angle of
(20 min)*(6 deg/min) = 120°
Because 360° = 2π radians,
120° = (120/360)*2π = (2π)/3 radians
Answer:
In decimals, this is 2.1 radians (nearest tenth)
Part 2:
Because the minute hand is 4 inches long, the length of the arc swept is
(4 in)*(2π/3 radians) = 8π/3 inches
Answer:
In decimals, this is 8.4 inches (nearest tenth).
That is, the minute hand creates
(360°/(60 min) = 6 degrees/min.
From 3:35 to 3:55 is 20 minutes.
It sweeps a central angle of
(20 min)*(6 deg/min) = 120°
Because 360° = 2π radians,
120° = (120/360)*2π = (2π)/3 radians
Answer:
In decimals, this is 2.1 radians (nearest tenth)
Part 2:
Because the minute hand is 4 inches long, the length of the arc swept is
(4 in)*(2π/3 radians) = 8π/3 inches
Answer:
In decimals, this is 8.4 inches (nearest tenth).
Remark.
The problem is a bit indistinct. Where exactly are the two edges of the road? I'm going to say that they are the x intercepts, but that may not be true. Certainly it does not have to be true at all.
Graph.
A graph has been made for you. The maximum is marked for you. It is an approximation The actual height can be more accurately found.
Height
y = (-1/200)(x - 16)(x + 16)
y = (-1/200)*(x^2 - 256)
The maximum height for this graph only is when x = 0.Other graphs require completing the square.
y = (-1/200) * (-256)
y = 1.28 exactly. I thought the graph might be rounding the answer. It is not.
