Wednesday
October 1, 2014

Homework Help: Trig(3 all with work)

Posted by Jon on Friday, February 15, 2008 at 3:17am.

1)Find the exact value of cos 105 by using a half-angle formula.
A)sqrt 2 - sqrt 3 /2
B)-sqrt 2 - sqrt 3 /2
C)-sqrt 2 + sqrt 3 /2
D)sqrt 2 + sqrt 3 /2

cos 105
cos 105 = cos 210/2
sqrt 1 + 210/2
sqrt 1 + sqrt 3/2 /2
sqrt 2 + sqrt 3/2 which is D

2)Find the solution of sin2 theta = cos theta if 0 -< theta < 180
A)30 degrees and 90 degrees
B)30 degrees and 150 degrees
C)30 degrees, 90 degrees, 150 degrees
D)0 degrees, 90 degrees, and 150 degrees

sin2 theta = cos theta
sin2 theta - 1 = 0
(sin theta + 1)(sin theta - 1)= 0
sin theta = -1 or sin theta = 1 which is B

3)An insect population P in a certain area fluctuates with the seasons. It is estimated that P = 17,000 + 4500 sin pi(t)/52, where t is given in weeks. Determine the number of weeks it would take for the population to initially reach 20,000.
A)12 weeks
B)692 weeks
C)38 weeks
D)42 weeks

P = 17,000 + 4500 sin pi(t)/52
20,000 = 17,000 + 4500 sin pi(t)/52
3,000 = 4500 sin pi(t)/52
.666 = sin pi(t)/52
The closest thing is C

Answer this Question

First Name:
School Subject:
Answer:

Related Questions

Calculus - Please look at my work below: Solve the initial-value problem. y'' + ...
Math/Calculus - Solve the initial-value problem. Am I using the wrong value for ...
Math Help please!! - Could someone show me how to solve these problems step by ...
Inequality - When I solve the inquality 2x^2 - 6 < 0, I get x < + or - ...
math,algebra,help - Directions are simplify by combining like terms. x radiacal ...
Mathematics - sqrt 6 * sqrt 8 also sqrt 7 * sqrt 5 6.92820323 and 5.916079783 So...
Math(Roots) - sqrt(24) *I don't really get this stuff.Can somebody please help ...
Math - How do you find a square root of a number that's not a perfect square? I'...
Calculus - Second Order Differential Equations - Posted by COFFEE on Monday, ...
TRIG - what is the exact value of sin^2 pi/6-2 sin pi/6 cos pi/6 +cos^2 (-pi/6...

Search
Members