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Irina18 [472]
3 years ago
15

Find cos(a), if cos(a)^4 - sin(a)^4 = 1/8

Mathematics
1 answer:
Alex17521 [72]3 years ago
5 0

Answer:

3/4, -3/4

Step-by-step explanation:

Using the difference of squares we can change things around.

cos(a)^4 - sin(a)^4

(cos^2(a) + sin^2(a))((cos^2(a) - sin^2(a)) then sin^2 + cos^2 = 1

cos^2(a) - sin^2(a) Using the same identity sin^2 = 1 - cos^2

cos^2(a) - (1 - cos^2(a))

cos^2(a) - 1 + cos^2(a)

2*cos^2(a) - 1

So let's use this.

2*cos^2(a) - 1 = 1/8

2*cos^2(a) = 9/8

cos^2(a) = 9/16

cos(a) = +/- 3/4

so 3/4 can be positive or negative

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Sandra throws an object straight up into the air with an initial velocity of 38 ft/s from a platform that is 30 ft above the gro
Makovka662 [10]

Answer:

The answer is C.

Step-by-step explanation:

Given formula h(t)=−16t2+v0t+h0 , where v0 is the initial velocity and h0 is the initial height.

In this case, the initial postion is a platform 30ft above ground so h0=+30

The initial velocity is 38 ft/s straight up into the air so v0=+38

h(t)=-16t2+38t+30

When the object hits the ground, h=0.

h=-16t2+38t+30=0

Simplifying 8t2-19t-15=0

(8t+5)(t-3)=0

t=-5/8 or 3

As time cannot be -ve, t=3s. The answer is C.

6 0
2 years ago
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If you lose two lbs a week consuming 600 calories, how many lbs would you lose consuming half of that?
SCORPION-xisa [38]

Answer:

maybe 4

Step-by-step explanation:

Well consider the fact a normal diet is about 1,200 calories a day. half of that is 600, there for you lose 2 pounds in a week. if you cut that in half the chances are you'll loose 4 pounds. but consuming only 300 calories a day is extremely unhealthy

4 0
3 years ago
The diagonal of a rectangle is 25 in. The width is 15 in. What is the area of the rectangle
djyliett [7]
Here is your answer > >

Width of rectangle =15 inches

Length of rectangle =?

Diagonal of rectangle = 25 inches

We know that

(Diagonal of rectagle)^2=length^2+breadth^2

(25)^2=l^2+(15)^2

625=l^2+225

l^2=625-225

l^2=400

l=Root 400

l=20 inches

Hope it helps!

Thankyou ☆ ☆

Bebrainly
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The product of a number and -3, increased by 8, is 20
natita [175]

answer:

-4

Step-by-step explanation:

-3x+8= 20

-8 -8

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Melissa read 4 books each week for 4 weeks. Amanda read 5 books a week for 4 weeks. How many more books did Amanda read?
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Amanda read 4 more books then Melissa.

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