Prove<br>that:<br>cos^3A Cos3A + sin^3A.sin 3A=cos^3 2A

Hitman42 [59]

This one is the Law of Sines again.

The Law of Sines relies on the standard labeling of triangle ABC with vertices A, B, and C and respective opposite sides of a, b and c. Then

$\dfrac{a}{\sin A} = \dfrac{b}{\sin B} = \dfrac{c}{\sin C}$

Here we have A=150 degrees (opposite side a), b= 10 cm and B = 12 degrees. We seek a.

So we need the first equation of the Law of Sines:

$\dfrac{a}{\sin A} = \dfrac{b}{\sin B}$

$a = \dfrac{b \sin A }{\sin B}$

$a = \dfrac{10 \sin 150}{\sin 12} \approx 28.0$

7 0

3 years ago

How many 25cm pieces of wires can<br>be cut out from a wire of length 4<br>metres?

Over [174]

Answer:

16

Step-by-step explanation:

4 meters is 400 centimeters and 400/25 is 16 so you can cut 16 pieces of 25cm wire from 4 meters of wire.

6 0

3 years ago

Read 2 more answers

The sum of two numbers is greater than 1. Which statement

Galina-37 [17]

Answer:

the sum of two whole numbers is always greater than either number because even if one of the numbers to be added is 0, the answer will, well, not be greater, but at least equal to it.

Step-by-step explanation:

plz mark as brainliest

5 0

3 years ago

The length of the diagonal of a square is 8 cm, how long are the sides of the square?

Svetach [21]

Answer:

5.66

Step-by-step explanation:

The sides of a square are equal. Let's call the length

x

Use Pythagoras' Theorem.

Square the sides and add them together....

x

2

+

x

2

=

8

2

x

2

=

64

x

2

=

64

2

=

32

x

=

√

32

x

=

4

√

2

x

=

5.66

8 0

4 years ago

Mrs. Wheeler had a bowl of M&M’s sitting on her table. Her daughter Lauren told her that she thought there were 100 M&M’

laiz [17]

There was 33.3% error in her calculation.

Step-by-step explanation:

Approx value thought by Lauren = 100

Exact value counted = 75

Percent error = $\frac{|approx-exact|}{exact}*100$

$Percent\ error=\frac{|100-75|}{75}*100\\\\Percent\ error=\frac{|25|}{75}*100\\\\Percent\ error=\frac{2500}{75}\\\\Percent\ error=33.33\%$

Rounding off to nearest tenth;

Percent error = 33.3%

There was 33.3% error in her calculation.

Keywords: percentage, error

Learn more about errors at:

#LearnwithBrainly

8 0

3 years ago

Provethat:cos^3A Cos3A + sin^3A.sin 3A=cos^3 2A​

Provethat:cos^3A Cos3A + sin^3A.sin 3A=cos^3 2A