Sunday

March 29, 2015

March 29, 2015

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 ...

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

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

physics - An earthquake generates three kinds of waves: surface waves (L waves...

physics - An earthquake generates three kinds of waves: surface waves (L waves...

physics - An earthquake generates three kinds of waves: surface waves (L waves...

PHYSICS - Waves - Can someone tell me how to get the answer to this question? ...

physics - An earthquake generates three kinds of waves: surface waves (L waves...

Physics - A pond is 12 metres across. The crests of two successive waves are 60....

Physics - A pond is 12 metres across. The crests of two successive waves are 60....