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Eduardwww [97]
3 years ago
14

Prove Sin3theta = 3sintheta - 4sin^3theta

Mathematics
1 answer:
trapecia [35]3 years ago
3 0

Express the left hand side as

sin3theta=sin(theta+2theta)

now expand the right side of this equation using color(blue)"Addition formula"

color(red)(|bar(ul(color(white)(a/a)color(black)(sin(A±B)=sinAcosB±cosAsinB)color(white)(a/a)|)))

rArrsin(theta+2theta)=sinthetacos2theta+costhetasin2theta.......(A)

color(red)(|bar(ul(color(white)(a/a)color(black)(cos2theta=cos^2theta-sin^2theta=2cos^2theta-1=1-2sin^2theta)color(white)(a/a)|)))

The right hand side is expressed only in terms of sintheta's

so we use cos2theta=1-2sin^2theta........(1)

color(red)(|bar(ul(color(white)(a/a)color(black)(sin2theta=2sinthetacostheta)color(white)(a/a)|)))........(2)

Replace cos2theta" and " sin2theta by the expansions (1) and (2)
into (A)

sin(theta+2theta)=sinthetacolor(red)((1-2sin^2theta))+costhetacolor(red)((2sinthetacostheta)

and expanding brackets gives.

sin(theta+2theta)=sintheta-2sin^3theta+2sinthetacos^2theta....(B)

color(red)(|bar(ul(color(white)(a/a)color(black)(cos^2theta+sin^2theta=1rArrcos^2theta=1-sin^2theta)color(white)(a/a)|)))

Replace cos^2theta=1-sin^2theta" into (B)"

rArrsin(theta+2theta)=sintheta-2sin^3theta+2sintheta(1-sin^2theta)

and expanding 2nd bracket gives.

sin(theta+2sintheta)=sintheta-2sin^3theta+2sintheta-2sin^3theta

Finally, collecting like terms.

sin3theta=3sintheta-4sin^3theta="R.H.S hence proven"
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1. Find the value of 8.3 x 24.2 x 0.03. Round your answer to the nearest hundredth.
MrMuchimi

The rounded value is option B) 6.03 which is rounded to the nearest hundredth.

<u>Step-by-step explanation:</u>

  • To find the value of 8.3 x 24.2 x 0.03, we need to multiply the given numbers to get a decimal value.
  • And then, after getting the value of 8.3 x 24.2 x 0.03 it should be rounded to the nearest hundredth.

<u>So, let's multiply the numbers first :</u>

8.3 × 24.2 × 0.03 = 6.0258

The value is 6.0258

<u>To round the value 6.0258 to the nearest hundredth :</u>

  • The first number next to the decimal point represents the tenth.
  • The second number next to the decimal point is the hundredth.
  • The third number next to the decimal point is thousandth.

Therefore, to round the value to the nearest hundredth, look for the thousandth number is either less than 5 or greater and or equal to 5.

If, thousandth place is greater or equal to 5, then the hundredth number should be increased by 1.

The hundredth is 6.02 and the number in the thousandth place is 5. So add 1 to the hundredth place.

The value is rounded to 6.03 to the nearest hundredth.

5 0
3 years ago
What value of x is in the solution set of 3(x – 4) ≥ 5x + 2? <br><br> –10<br> –5<br> 5<br> 10
emmasim [6.3K]

<u>Answer:</u>

The value of x is in the solution set of 3(x – 4) ≥ 5x + 2 is -10

<u>Solution:</u>

Need to determine which value of x from given option is solution set of 3(x – 4) ≥ 5x + 2

Lets first solve 3(x – 4) ≥ 5x + 2

3(x – 4) ≥ 5x + 2

=> 3x – 12 ≥ 5x + 2

=> 3x – 5x ≥ 12 + 2

=> -2x ≥ 14

=> -x ≥ 7

=> x ≤ -7

All the values of x which are less than or equal to -7 is solution set of 3(x – 4) ≥ 5x + 2. From given option there is only one value that is -10 which is less than -7  

Hence from given option -10 is solution set of 3(x – 4) ≥ 5x + 2.

7 0
3 years ago
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9,032,504.75 in word form
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Nine million thirty-two thousand five hundred four and seventy-five hundredths
6 0
3 years ago
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Identify each expression with a sum of x2 + 3x +1.
Yuki888 [10]

Answer:

There are no like terms.

Step-by-step explanation:

5 0
3 years ago
The dance team traveled to a competition and traveled in two vans. The first van transported 2 adults and 5 students and cost $7
Shtirlitz [24]

Answer: $9

Step-by-step explanation:

Let the cost for adults be a

Let the cost for students be b.

The first van transported 2 adults and 5 students and cost $77. This will be:

2a + 5b = $77

The second van transported 2 adults and 7 students and cost $95. This will be:

2a + 7b = $95

2a + 5b = 77 ...... equation i

2a + 7b = 95 ........ equation ii

Subtract equation ii from I

-2b = -18

b = 18/2

b = $9

An student cost $9

Put the value of b into equation i

2a + 5b = 77

2a + 5(9) = 77

2a + 45 = 77

2a = 77 - 45

2a = 32

a = 32/2

a = 16

An adult costs $16

5 0
3 years ago
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