Posted by **Kelsey** on Monday, May 28, 2012 at 2:56pm.

1. Which expression is equivalent to cos 2theta for all values of theta ?

cos^2 theta – sin^2 theta ~

cos^2 theta – 1

1 – 2 sin^2 theta

2 sin theta cos theta

2. Use a half–angle identity to find the exact value of sin 105°.

-1/2(sqrt)(2 + Sqrt3)

1/2(sqrt)(2 + Sqrt3) ~

1/2(sqrt)(2 + Sqrt2)

11/2(sqrt)(1 + Sqrt3)

3.) Solve cos x tan x - sin^2x = 0 for all real values of x.

piK, pi/2 + 2piK

pi/2 + piK, 2pik

pi/2 + 2piK, 3pi/2 + 2piK

piK, pi/4 +2piK ~

4.) Solve 2 sin2x – sin x = 0 for principal values of x.

60° and 120°

0° and 150° ~

0° and 30°

60°

5.) Solve csc x + 2 = 0 for 0 < x < 2pi.

pi/6 and 5pi/6

pi/6 and 7pi/6

4pi/3 and 5pi/3

7pi/6 and 11pi/6 ~

6.) Solve 2 cos x – 1 = 0 for 0 <x< 2.

pi/6 and 5pi/6

pi/3 and 5pi/3 ~

pi/3 and 2pi/3

7pi/6 and 11pi/6

7.) Write the equation 3x + 4y – 7 = 0 in normal form.

3/5x + 4/5y + 7/5 = 0

-3/5x - 4/5y - 7/5 = 0

-3/5x - 4/5y + 7/5 = 0 ~

3/5x + 4/5y - 7/5 = 0

8.)Write the standard form of the equation of a line for which the length of the normal is 4 and the normal makes an angle of 45° with the positive x–axis.

sqrt2x + sqrt2y +8 = 0

2x + 2y – 8 = 0

sqrt2x + sqrt2y -8 = 0 ~

2x + 2y + 8 = 0

9.) Write the standard form of the equation of a line for which the length of the normal is 3 and the normal makes an angle of 135° with the positive x–axis.

sqrt2^x – sqrt2y + 6 = 0 ~

sqrt2^x + sqrt2y - 6 = 0

sqrt2^x – sqrt2y - 6 = 0

sqrt2^x + sqrt2y + 6 = 0

10.) Find the distance between P (–2, 1) and the line with equation x – 2y + 4 = 0.

4sqrt5/5

0 ~

-4sqrt5/5

5/4

the ones with~ are my answers

- Precalculus check answers help! -
**Steve**, Monday, May 28, 2012 at 4:13pm
#3 should be piK, pi/2 + 2piK since sin=0 or 1

#4. should be 0° and 30° since they asked for principal values

1,2,5,6 look good

7-10 I'll have to check later, or another expert can come by.

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