Can someone please help me on 20 and 21

He formula for density is given by , where p is density, M is mass and V is volume. If a substance has a mass of 27.82 grams and

Vera_Pavlovna [14]

Answer:

p = [27.82] ÷ [3.6]

p = 7.727·

p = 7.728 (3dp)

The answer is B)

Step-by-step explanation:

5 0

3 years ago

Read 2 more answers

Derive these identities using the addition or subtraction formulas for sine or cosine: sinacosb=(sin(a+b)+sin(a-b))/2

Sergeu [11.5K]

Answer:

The work is in the explanation.

Step-by-step explanation:

The sine addition identity is:

$\sin(a+b)=\sin(a)\cos(b)+\cos(a)\sin(b)$ .

The sine difference identity is:

$\sin(a-b)=\sin(a)\cos(b)-\cos(a)\sin(a)$ .

The cosine addition identity is:

$\cos(a+b)=\cos(a)\cos(b)-\sin(a)\sin(b)$ .

The cosine difference identity is:

$\cos(a-b)=\cos(a)\cos(b)+\sin(a)\sin(b)$ .

We need to find a way to put some or all of these together to get:

$\sin(a)\cos(b)=\frac{\sin(a+b)+\sin(a-b)}{2}$ .

So I do notice on the right hand side the $\sin(a+b)$ and the $\sin(a-b)$ .

Let's start there then.

There is a plus sign in between them so let's add those together:

$\sin(a+b)+\sin(a-b)$

$=[\sin(a+b)]+[\sin(a-b)]$

$=[\sin(a)\cos(b)+\cos(a)\sin(b)]+[\sin(a)\cos(b)-\cos(a)\sin(b)]$

There are two pairs of like terms. I will gather them together so you can see it more clearly:

$=[\sin(a)\cos(b)+\sin(a)\cos(b)]+[\cos(a)\sin(b)-\cos(a)\sin(b)]$

$=2\sin(a)\cos(b)+0$

$=2\sin(a)\cos(b)$

So this implies:

$\sin(a+b)+\sin(a-b)=2\sin(a)\cos(b)$

Divide both sides by 2:

$\frac{\sin(a+b)+\sin(a-b)}{2}=\sin(a)\cos(b)$

By the symmetric property we can write:

$\sin(a)\cos(b)=\frac{\sin(a+b)+\sin(a-b)}{2}$

3 0

3 years ago

Questions 1-6 , need help ASAP , will award you brainiest

nika2105 [10]

Answer:

1. 13+10i

2. 28-(-4i)

3. -14-1i

4. 4 -i

5. 15+ 10i

6.8 - 5i^2

Step-by-step explanation:

8 0

3 years ago

Find the value of Z for the triangles

kolbaska11 [484]

Answer:

z = 17.5

Step-by-step explanation:

segment RX is an angle bisector and divides the opposite side into segments that are proportional to the other 2 sides, that is

$\frac{RS}{RT}$ = $\frac{SX}{TX}$ , substitute values

$\frac{15}{z}$ = $\frac{6}{7}$ ( cross- multiply )

6z = 105 ( divide both sides by 6 )

z = 17.5

4 0

3 years ago

Someone PLEASEEEE HELPPPP

igomit [66]

Answer:

x = 18√3

Step-by-step explanation:

From the picture attached,

In a right triangle,

Measure of one angle = 30°

Measure of adjacent side of the angle = 9 units

We have to find the measure of Hypotenuse from the given properties.

By cosine rule,

cos(30°) = $\frac{\text{Adjacent side}}{\text{Hypotenuse}}$

$\frac{\sqrt{3}}{2} =\frac{9}{x}$

$x=18\sqrt{3}$

Therefore, measure of Hypotenuse is 18√3 units.

3 0

3 years ago