Question

A Cepheid variable star is a star whose brightness alternately increases and decreases. For a certain star, the interval between times of maximum brightness is 3.5 days. The average brightness of this star is 4.0 and its brightness changes by ±0.25. In view of these data, the brightness of the star at time t, where t is measured in days, has been modeled by the function B(t) = 4.0 + 0.25 sin(2?t / 3.5). (a) Find the rate of change of the brightness after t days. dB/dt = (0.25 cos(2?t / 3.5)) * 2?/3.5 = (5? / 35) cos(2?t / 3.5) (b) Find, correct to two decimal places, the rate of increase after three days. dB/dt = 0.28

          A Cepheid variable star is a star whose brightness alternately increases and decreases. For a certain star, the interval between times of maximum brightness is 3.5 days. The average brightness of this star is 4.0 and its brightness changes by ±0.25. In view of these data, the brightness of the star at time t, where t is measured in days, has been modeled by the function

B(t) = 4.0 + 0.25 sin(2?t / 3.5).

(a) Find the rate of change of the brightness after t days.
dB/dt = (0.25 cos(2?t / 3.5)) * 2?/3.5 = (5? / 35) cos(2?t / 3.5)

(b) Find, correct to two decimal places, the rate of increase after three days.
dB/dt = 0.28

A Cepheid variable star is a star whose brightness alternately increases and decreases. For a certain star, the interval between times of maximum brightness is 3.5 days. The average brightness of this star is 4.0 and its brightness changes by ±0.25. In view of these data, the brightness of the star at time t, where t is measured in days, has been modeled by the function

B(t) = 4.0 + 0.25 sin(2?t / 3.5).

(a) Find the rate of change of the brightness after t days.
dB/dt = (0.25 cos(2?t / 3.5)) * 2?/3.5 = (5? / 35) cos(2?t / 3.5)

(b) Find, correct to two decimal places, the rate of increase after three days.
dB/dt = 0.28

Added by Cassie T.

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