Discussion about math, puzzles, games and fun. Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ π -¹ ² ³ °

You are not logged in.

- Topics: Active | Unanswered

Pages: **1**

If in a triangle,

Then,

What is the value of sin angle A?

Is it 8/27?

'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

'You have made another human being happy. There is no greater accomplishment.' -bobbym

Offline

**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 6,469

hi Agnishom

How did you get that? It's not what I'm getting.

Here's my method.

SINE RULE is:

So I put

and re-arranged to get

Different values of k will make different sized circles but all the resulting triangles will be similar => same three angles.

So it is ok to take a = √6, b = 2√2, c = 3√3

Use the cosine rule to get cosA and hence sinA.

I made it

Bob

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

Offline

bob bundy wrote:

hi Agnishom

SINE RULE is:

So I put

and re-arranged to get

I have the following doubts:

I. How did you do the rearrangement?

II. How do you know what to put for a?

'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

'You have made another human being happy. There is no greater accomplishment.' -bobbym

Offline

Okay thanks I managed to understand this

'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

'You have made another human being happy. There is no greater accomplishment.' -bobbym

Offline

**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 6,469

hi Agnishom,

Glad you understand it. Your method and mine are essentially the same; I used k; you have t; and then I let k=1. In yours the t cancels out.

Bob

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

Offline

Yeah Thanks! I had difficulty understanding the cancellation

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

'You have made another human being happy. There is no greater accomplishment.' -bobbym

Offline

**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 6,469

Two triangles with sides in the same ratio are similar. So the angles are the same. Therefore you can just call t = 1 without losing any of the problem's conditions.

That's why it cancels out of the cosine rule step.

Bob

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

Offline

Pages: **1**