All categories

3 years ago

Prove the identity cos(x-y)-cos(x+y)=2sinx siny

Mathematics

1 answer:

True [87]3 years ago

8 0

Answer:

see explanation

Step-by-step explanation:

Using the Addition/ Subtraction formulae for cosine

Consider the left side

cos(x - y) - cos(x + y)

= cosxcosy + sinxsiny - (cosxcosy - sinxsiny) ← distribute

= cosxcosy + sinxsiny - cosxcosy + sinxsiny ← collect like terms

= 2sinxsiny = right side ⇒ proven

You might be interested in

Please can u answer these for me

ziro4ka [17]

18 . it's increasing by 5 every time so the next one after 23 is 28

4 0

3 years ago

Help pleaseeee thank you

fenix001 [56]

Answer:

Can't read the picture. Please take a bigger picture of the triangle.

8 0

3 years ago

What is the solution for the equation -15=5(3y-10)-5y

marissa [1.9K]

Answer:

$\Large\boxed{\sf{y=\dfrac{7}{2} }}$

Step-by-step explanation:

Isolate the variable of y from one side of the equation.

-14=5(3y-10)-5y

First, switch sides.

$\sf{5\left(3y-10\right)-5y=-15}$

Use the distributive property.

DISTRIBUTIVE PROPERTY:

A(B-C)=AB-AC

5(3y-10)

Multiply by expand.

5*3y=15y

5*10=50

15y-50-5y

15y-5=10y

= 10y-50

10y-50=-15

Add by 50 from both sides.

10y-50+50=-15+50

Solve.

10y=35

Then, you divide by 10 from both sides.

10y/10=35/10

Solve.

Divide the numbers from left to right.

35/10=7/2

y=7/2

Divide is another option.

7/2=3.5

$\Longrightarrow: \boxed{\sf{y=\dfrac{7}{2}}}$

Therefore, the correct answer is y=7/2.

I hope this helps. Let me know if you have any questions.

7 0

2 years ago

70 POINTS HELP ME URGENT SHOW YOUR WORK

Feliz [49]

Answer:

x= the number of ride tickets

y= the total cost of admission plus how many ride tickets a person purchases

y= 1.25x + 9.5

It is a$1.25 per ticket for the rides at the fair, so it would be 1.25 multiplied by the amount of tickets that are purchased (x). Spencer bought 17 tickets, so 17x1.25= 21.25 and it says that he spent a total of $30.75 at the fair, so 30.75-21.25=9.5, so that means the cost of admission is $9.50.

Step-by-step explanation:

I hope this helps!

7 0

2 years ago

Jordan is another employee at the same coffee shop. He has worked there longer than Gabe and earns $3 more per hour than Gabe. C

ANEK [815]

Answer:

I think we need to see something

8 0

3 years ago