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Step2247 [10]
3 years ago
12

What are the solutions to cos 2x = - 1​

Mathematics
1 answer:
N76 [4]3 years ago
4 0

Answer:

X can be - 1/2 or 0.5

2x0.5=-1

Step-by-step explanation:

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the price of an item has been reduced by $2.72 . the new sale price is $96.09 . what was the original price?
stellarik [79]
You add the two numbers together and get $98.81
6 0
3 years ago
This is finding exact values of sin theta/2 and tan theta/2. I’m really confused and now don’t have a clue on how to do this, pl
Lostsunrise [7]

First,

tan(<em>θ</em>) = sin(<em>θ</em>) / cos(<em>θ</em>)

and given that 90° < <em>θ </em>< 180°, meaning <em>θ</em> lies in the second quadrant, we know that cos(<em>θ</em>) < 0. (We also then know the sign of sin(<em>θ</em>), but that won't be important.)

Dividing each part of the inequality by 2 tells us that 45° < <em>θ</em>/2 < 90°, so the half-angle falls in the first quadrant, which means both cos(<em>θ</em>/2) > 0 and sin(<em>θ</em>/2) > 0.

Now recall the half-angle identities,

cos²(<em>θ</em>/2) = (1 + cos(<em>θ</em>)) / 2

sin²(<em>θ</em>/2) = (1 - cos(<em>θ</em>)) / 2

and taking the positive square roots, we have

cos(<em>θ</em>/2) = √[(1 + cos(<em>θ</em>)) / 2]

sin(<em>θ</em>/2) = √[(1 - cos(<em>θ</em>)) / 2]

Then

tan(<em>θ</em>/2) = sin(<em>θ</em>/2) / cos(<em>θ</em>/2) = √[(1 - cos(<em>θ</em>)) / (1 + cos(<em>θ</em>))]

Notice how we don't need sin(<em>θ</em>) ?

Now, recall the Pythagorean identity:

cos²(<em>θ</em>) + sin²(<em>θ</em>) = 1

Dividing both sides by cos²(<em>θ</em>) gives

1 + tan²(<em>θ</em>) = 1/cos²(<em>θ</em>)

We know cos(<em>θ</em>) is negative, so solve for cos²(<em>θ</em>) and take the negative square root.

cos²(<em>θ</em>) = 1/(1 + tan²(<em>θ</em>))

cos(<em>θ</em>) = - 1/√[1 + tan²(<em>θ</em>)]

Plug in tan(<em>θ</em>) = - 12/5 and solve for cos(<em>θ</em>) :

cos(<em>θ</em>) = - 1/√[1 + (-12/5)²] = - 5/13

Finally, solve for sin(<em>θ</em>/2) and tan(<em>θ</em>/2) :

sin(<em>θ</em>/2) = √[(1 - (- 5/13)) / 2] = 3/√(13)

tan(<em>θ</em>/2) = √[(1 - (- 5/13)) / (1 + (- 5/13))] = 3/2

3 0
2 years ago
What is the volume of a ball that has a diameter of 9 inches? Round to the nearest whole number
nalin [4]
Ball=sphere
Vsphere=pir^3
d/2=r
d=9
9/2=4.5=r
V=pi4.5^3
V=pi91.125
aprox pi=3.141592
V=286.227
round
V=286 in^3
4 0
3 years ago
What is the value of A when we rewrite 1.44^1.2x as A^x​
Lina20 [59]

Answer:

a = 0.64

Step-by-step explanation:

hope that helped

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2 years ago
Can a triangle be formed with the side lengths of 4, 5, and 7 units
KATRIN_1 [288]

Answer:

Step-by-step explanation:

7 0
3 years ago
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