GARDENING EXPRESS PROBLEMS
Posted on Tuesday, June 1st, 2010 at 6:58 am
math help, please, trig. and words problems!!!!!!!!?
1. solve: 2(sin^2)x – 3cos x = 3
2. a rectangular garden that has an area of 100 ft^2 is bounded on 3 sides by a brick wall costing $50 per foot and on the fourth side by a fence costing only $20 per foot, express the cost of the garden’s enclosure in terms of the single variable x, where x is the length of the fence side.
3. Laura traveled for h hours at m mph but arrived at the fjord 2 hours late. how fast should Laura have traveled to have arrived on time? ( hint: figure out the distance Laura had to travel , and use the fact that distance is the product of rate and time.
1. solve: 2(sin^2)x – 3cos x = 3
sin^2 x = 1 – cos^2 x
substitute
2(1-cos^2 x) – 3cosx =3
2 – 2cos^2 x – 3cosx = 3
- 2cos^2 x – 3cosx = 3 -2
- 2cos^2 x – 3cosx = 1
- 2cos^2 x – 3cosx – 1 = 0
2cos^2 x + 3cosx + 1 = 0
let y = cos x
2y^2 + 3y + 1 = 0
(2y +1)(y + 1)= 0
y = -1/2
y = -1
cosx = -1/2
x = -pi/6
cos x = -1
x = pi
2. a rectangular garden that has an area of 100 ft^2 is bounded on 3 sides by a brick wall costing $50 per foot and on the fourth side by a fence costing only $20 per foot, express the cost of the garden’s enclosure in terms of the single variable x, where x is the length of the fence side.
A = 100 = xy
C = 50(2x) + 50y + 20y
C = 100x + 70y
C = 100x + 70(100/x)
C = 100x + 7000/x
3. s = d/t
s = speed
d = distance in miles
t= the time in hours
s1 is the speed when late by 2 h
s2 = is the speed needed to be on time
s1 = d/(t+2)
s2 = d/t
d=d
s1(t+2) = s2 t
s2 = s1(t+2)/t
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