# Graphical question [Solved!]

**mfaisal_1981** 11 Jul 2016, 06:34

### My question

In the above given triangle when `theta` = 0 then b=c

But when `theta` = 90 then d=0

Since d is the projection of b

How we can derive a generalised formula for d or c-d with respect to `theta`

Plese may kindly be elaborated

### Relevant page

1. Distance Formula

### What I've done so far

X

<img src="/forum/uploads/imf-3408-triangle-question-image2.png" width="261" height="131" alt="trigonometric-graphs" />
In the above given triangle when `theta` = 0 then b=c
But when `theta` = 90 then d=0
Since d is the projection of b
How we can derive a generalised formula for d or c-d with respect to `theta`
Plese may kindly be elaborated

Relevant page
<a href="/plane-analytic-geometry/1-distance-formula.php">1. Distance Formula</a>
What I've done so far

## Re: Graphical question

**Murray** 12 Jul 2016, 07:51

Hello mfaisal

I can't see any working, so I'm not sure where you are getting stuck. Always show some steps so we can better help you.

The question seems a bit strange to me. Surely if `b=c`. then it won't matter what the angle `theta` is?

X

Hello mfaisal
I can't see any working, so I'm not sure where you are getting stuck. Always show some steps so we can better help you.
The question seems a bit strange to me. Surely if `b=c`. then it won't matter what the angle `theta` is?

## Re: Graphical question

**Murray** 08 Sep 2016, 22:50

mfaisal did not reply.

A generalised formula would need to use trigonometry, I believe, something like

`tan theta = h/d`

I'm not sure there is any more "generalised" way to answer it.

X

mfaisal did not reply.
A generalised formula would need to use trigonometry, I believe, something like
`tan theta = h/d`
I'm not sure there is any more "generalised" way to answer it.

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