hi guys, my name is senait and I am today scribe. Today pre cal class was in the afternoon during period 4 and it was kind of quite class because we had review yesterday on transformation and the word problem was difficult to solve. The review was

2 The depth of water in a harbour can be approximated by the equation: d(t)= -3.5cos0.17pi t+12 where d(t) is the depth in meters, and t is the time, in hours, after low tide.

(a) graph the function without using your calculator?

(b) what is the period of the function? What does it tell you about the tide?

(c) an ocean liner needs a minimum of 13m of water to dock safely. For how many hours per cycle can the ocean liner dock safely?

(b) P=2pi/B

=2pi/0.17

=1.76

(c) 13= -3.5cos0.17pi t+12

1= -3.5cos(0.17pi t)

1/-3.5=cos(0.17pi t) we can think as sta

0.17pi t/0.17pi = 1.8605/0.17pi

t= 3.48

pi-1.8605 to get alfa

alfa=1.2816

pi-alfa= 4.4227

0.17pi t/0.17pi = 4.4227/0.17pi

t = 8.2811

To find hours : 8.2811-3.48= 4.797

4.797-4 = 0.797

0.797*60 = 47.82

3. The average daily maximum temperature in Victoria B.C reaches a high of 23 C on July27, and a low of 5 dgreeC on January 5.

(a) Model this situation using a sine and a cosine function.

(b) Graph the function without using your calculator.

(c) How many days will have an expected maximum of 20 degrees or higher?

July 27, max 23 degrees

January 5, min 5 degrees

Jan/31, Feb/28, Mar/31, Apr/30, May/31, June/30, July/27 =208

period=406

T(d)= 9sin[2pi/406(t-106.5)]+14

T(d)= -9sin[2pi/406(t-5)]+14

the next scribe id Zaenab.

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