# Previous answers scalcet7 34081 a cepheid variable

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15.2/2 points | Previous AnswersSCalcET7 3.4.081.A Cepheid variable star is a star whose brightness alternately increases and decreases. For a certainstar, the interval between times of maximum brightness is 6.1 days. The average brightness of this staris 4.0 and its brightness changes by ±0.55. In view of these data, the brightness of the star at time where tis measured in days, has been modeled by the function(a) Find the rate of change of the brightness after tdays.(t) = 4.0 + 0.55 sin.2πtt,(b) Find, correct to two decimal places, the rate of increase after five days.Solution or ExplanationClick to View SolutionB(t) = 4.0 + 0.55 sin.2πt6.1
dt
12/14/16, 4(11 PMhw12S3.4Page 11 of 1116.4/4 points | Previous AnswersIf we plot the points (x,y)satisfying the equation 24+y2= 1, the result is an ellipse. This ellipse ispictured, along with a line that is tangent to the ellipse at Pand passes through the point Q=(4,0)The equation of the line is:y=\$\$123x +\$\$123+32.x.
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