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Luba_88 [7]
3 years ago
13

Prove that sin20sin40sin60sin80=3/16

Mathematics
1 answer:
never [62]3 years ago
5 0
We'll use the following properties of sine and cosine to prove this:

sin(a)\cdot sin(b) = \frac12(cos(a-b) - cos(a+b))

cos(a)\cdot cos(b) = \frac12(cos(a+b) + cos(a-b))

cos(180+a) = cos(180-a)

Then it's just a matter of filling it in...

sin20sin40 * sin60sin80 = 1/2(cos20 - cos60) * 1/2 (cos20 - cos140) =

1/8( cos40 + 1 - cos160 - cos120 - cos40 - cos80 + cos80 + cos200) =

1/8(1 -  cos160 - cos120 + cos200) =

1/8(1 -  cos160 - cos120 + cos160) =

1/8(1 - cos120 ) = 1/8( 1 + 1/2 ) = 3/16

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A press release describing the 1986 nonstop, round-the-world trip by the aircraft voyager including the following data:
adoni [48]

Answer:

a.) the average speed of the aircraft in miles per hour

115.76 miles/ hour

b.) the fuel consumption in miles per pound of fuel

(assume a density of 0.70 g/mL for the fuel.)

2.8 miles/Ib of fuel

Step-by-step explanation:

A press release describing the 1986 nonstop, round-the-world trip by the aircraft voyager including the following data:

flight distance: 25,012 miles

flight time: 9 days, 3 min., 44 seconds

fuel capacity: nearly 9000 lbs.

fuel remaining at the end of flight: 14 gal.

To the maximum number of significant figure permitted, calculate:

a.) the average speed of the aircraft in miles per hour

Step 1

We convert the time to hours

flight time: 9 days, 3 min., 44 seconds

1 day = 24 hours

9 days =

24 × 9

= 216 hours

60 mins = 1 hour

3 mins =

3/60 = 1/20 = 0.05 hours

1 hour = 60 minutes

1 minute = 60 seconds

1 hour = 60 × 60 = 3600 seconds

If 3600 seconds = 1 hour

44 seconds =

= 44/3600

= 0.0122222222 hours

Total number of hours spent = (216 + 0.05 + 0.0122222222) hours

= 216.06222222 hours

Speed = Distance/Time

= flight distance: 25,012 miles

Speed = 25,012 miles/ 216.06222222hours

= 115.76294895 miles/ hour

Approximately = 115.76 miles/ hour

b.) the fuel consumption in miles per pound of fuel

(assume a density of 0.70 g/mL for the fuel.)

Step 1

We determine how much fuel is used

We have 14 gallons of fuel left over

1 gallon = 3.785 litres

14 gallons =

Cross Multiply

14 gallons × 3.785 liters/1 gallon

= 52.9958 liters

Note that density of fuel =

0.70 g/ml

1 gram / millilitre = 1 kilogram / litre

Hence, 0.7g/ml = 0.7 kg/L

Hence,the mass of fuel left = 52.9958 liters * 0.7 = 37.09706kg

1 kilogram = 2.205 pounds

37.09706kg =

37.09706kg × 2.205 pounds

= 81.7990173 lbs

Since the full capacity = 9000 lbs

The fuel used = 9000 - 81.7990173 lbs

= 8918.2009827 lbs

Hence, fuel consumption is

Distance/ amount of fuel used

25012/8918.2009827 lbs = 2.8046015164 miles/lb of fuel

Approximately = 2.8 miles/Ib of fuel

7 0
3 years ago
**WILL MARK BRAINLIEST** PLEASE ANSWER!! please ??
geniusboy [140]

Answer:

Port eagle has the higher median

Step-by-step explanation:

That's all I will give you.

Why?

Because the median is the average which would be the middle range between two points.

7 0
3 years ago
1.Find the area of a circle with the radius of 48mm
OLga [1]

Answer:

hope it helps you see the attachment for further information....

3 0
3 years ago
How do you solve twelve less than the quotient of a number and 7 is -2
Drupady [299]

Remark

One of the things you need to do is learn to read phrase by phrase.

What is the quotient of a number and 7? That meas you have a number, x, and it is divided by 7. What you do that the answer you get is the quotient.

x/7 is what you know so for. Now the first part says you take 12 away from that.

x/7 - 12 is what you have after doing that.

The result you get is - 2

x/7 - 12 = - 2 Add 12 to both sides

x/7 - 12 + 12 = - 2 + 12

x/7 = 10 Now multiply by 7

x = 10 *7

x = 70 <<< Answer the number is 70


6 0
3 years ago
Will give 5 star, thanks, and brainliest for correct answers
algol13
1) X=159
2) BCD=103
3) DCH=89
im pretty sure


7 0
3 years ago
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