The base of a triangle is decreasing at a rate of 13 millimeters per minute and the height of the triangle is increasing at a rate of 6 millimeters per minute.At a certain instant, the base is 5 millimeters and the height is 1 millimeter.What is the rate of change of the area of the triangle at that instant (in square millimeters per minute)?Choose 1 answer:(A) −8.5(B) 8.5(C) −21.5(D) 21.5
Q. The base of a triangle is decreasing at a rate of 13 millimeters per minute and the height of the triangle is increasing at a rate of 6 millimeters per minute.At a certain instant, the base is 5 millimeters and the height is 1 millimeter.What is the rate of change of the area of the triangle at that instant (in square millimeters per minute)?Choose 1 answer:(A) −8.5(B) 8.5(C) −21.5(D) 21.5
Area Formula: The area of a triangle is given by the formula A=21×base×height.
Derivative Calculation: Let's denote the base by b and the height by h. The rate of change of the area with respect to time t can be found using the derivative dtdA=21⋅(dtdb⋅h+b⋅dtdh).
Given Rates: Given dtdb=−13 mm/min (since the base is decreasing) and dtdh=6 mm/min (since the height is increasing).
Instant Values: At the instant when the base b is 5mm and the height h is 1mm, we plug these values into the derivative formula to find dtdA.
Calculate dtdA: So, dtdA=21×(−13×1+5×6).
Final Result: Calculating the above expression gives dtdA=21×(−13+30).
Final Result: Calculating the above expression gives dtdA=21×(−13+30). dtdA=21×17=8.5 square millimeters per minute.
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