Saturday

September 20, 2014

September 20, 2014

Posted by **Melinda** on Thursday, January 19, 2012 at 3:36pm.

1. A person waves his hand back and forth, where their finger tips move past the starting position 4 cm in each direction. If he waves 20 times every 15s, what sine equation models the movement of the hand if the hand starts in the upright position and the right direction will be taken as positive?

a)y=4sin(20pi/15 x t)

b)y=4sin(30pi/20 x t)

c)y=4sin(40pi/15 x t)

c)y=8sin(30pi/20 x t)

Answer: A

--------------------------------------

2. Which of the six trig functions are positive in quad III?

Ans: Tangent and cotangent

---------------------------------------

3. What is the exact value of sin(3pi/2)?

Answer: 3pi/2=270 degree, equals to -1

Therefor exact value -1.

---------------------------------------

- Math -
**Steve**, Thursday, January 19, 2012 at 4:14pm1.

If he waved once every second, the frequency would be 1. you'd have sin(2πt).

If he waved n times, you'd have sin(2πnt).

Would you like to change your answer to C?

2. ok

3. ok

- Math - PS -
**Steve**, Thursday, January 19, 2012 at 4:16pmHmm. If a wave is defined as moving away from the starting point and back, your A answer is correct.

If a wave is defined as a complete cycle away and back in each direction, then the answer would be C.

- Math -
**jake**, Thursday, January 19, 2012 at 4:24pmI am confused for number 3

- Math -
**Steve**, Thursday, January 19, 2012 at 4:40pmsin(270) = sin(90+180) = sin90cos180 + cos90sin180 = 1(-1) + 0*0 = -1

or, at 270 deg, y=-1, x=0, r=1

sin = y/r = -1/1 = -1

**Answer this Question**

**Related Questions**

Math - A swing has a maximum height of 2 m and a minimum height of 0.5 m and it ...

English Expressions - Spread your fingers. This is the thumb, this is the index ...

physics - As your hand moves back and forth to generate longitudinal pulses in a...

physics - Q1-In hugyen's principle of wave theory why the waves are move in ...

Physical Science - Here are a few questions that I have answered; can someone ...

english - Put an accent mark above the strong beats in the first four lines of ...

Engish - I would like to know about some gestures. 1. If somebody puts his ...

Physical Science - If you were to expend 10 Joules of work to push a 1-coulomb ...

physics - A woman holds a 1.9 m long uniform 5.5 kg pole as shown in the figure...

Physics - A woman holds a 1.9 m long uniform 5.5 kg pole as shown in the figure...