Math Is Fun Forum

malaysiawill

Member

Registered: 2016-05-23

Posts: 43

Re: Geometry review.

What is the length of the line segment with endpoints (-8,6) and (-10,-1)?
Okay, thank you, enjoy your day.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Geometry review.

Hi;

You use the distance formula for that. I am getting

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

malaysiawill

Member

Registered: 2016-05-23

Posts: 43

Re: Geometry review.

18. In the diagram shown, a 12-foot slide is attached to a swing set. The slide makes a 65 degree angle with the swing set. What is the height of the top of the slide (as close as you can get)?

sin 65 degree = 0.91
cos 65 degree = o.42
tan 65 degree = 2.14

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Geometry review.

Use the Cosine of 65 degrees.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

malaysiawill

Member

Registered: 2016-05-23

Posts: 43

Re: Geometry review.

What do you mean? I don't understand what formula I would be using to get the answer.

zetafunc

Moderator

Registered: 2014-05-21

Posts: 2,436

Website

Re: Geometry review.

Are you familiar with SOH-CAH-TOA?

malaysiawill

Member

Registered: 2016-05-23

Posts: 43

Re: Geometry review.

a little. we did one lesson on it.
sin = opp./hyp.
cos = adj./hyp.
tan = opp./adj.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Geometry review.

The cos(65 degrees) = adj / hypotenuse which is x / hypotenuse. Can you finish up?

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

malaysiawill

Member

Registered: 2016-05-23

Posts: 43

Re: Geometry review.

cos(65 degrees) = x/12
cos(780)=x

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Geometry review.

What is 780?

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

malaysiawill

Member

Registered: 2016-05-23

Posts: 43

Re: Geometry review.

I did 65 * 12.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Geometry review.

Let all units be in degrees.

12 cos(65) does not equal cos(780). You can not multiply through a cosine like that.

Let us go back a bit:

cos(65 degrees) = x/12

Know how to get cos(65°)?

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

malaysiawill

Member

Registered: 2016-05-23

Posts: 43

Re: Geometry review.

oh okay. no I don't know hot to get cos(65)

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Geometry review.

In the old days we had to look it up in a table, nowadays we have computers, calculators and the internet. You are luckier, try google.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

malaysiawill

Member

Registered: 2016-05-23

Posts: 43

Re: Geometry review.

cos(65)=0.42

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Geometry review.

You can do a bit better than that

cos(65) = .42261826

So substituting in cos(65 degrees) = x/12 we get what?

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

malaysiawill

Member

Registered: 2016-05-23

Posts: 43

Re: Geometry review.

well that's what my teacher put in the question, so I didn't write the whole number.

so:
cos(65) = x/12
.42=x/12?

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Geometry review.

Okay, solve it please...

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

malaysiawill

Member

Registered: 2016-05-23

Posts: 43

Re: Geometry review.

cos(65) = x/12
.42=x/12
5.04=x

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Geometry review.

You have solved for x, very good!

So what is the answer to post #28?

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

malaysiawill

Member

Registered: 2016-05-23

Posts: 43

Re: Geometry review.

the height is 5.04?

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Geometry review.

5.04 what?

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

malaysiawill

Member

Registered: 2016-05-23

Posts: 43

Re: Geometry review.

5.04 ft?

malaysiawill

Member

Registered: 2016-05-23

Posts: 43

Re: Geometry review.

20. Calculate the area of the shaded region in the figure shown.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Geometry review.

That is correct!

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.