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**

**romani****Member**- Registered: 2013-06-28
- Posts: 3

Okay, so I've found this geometry question that's making me crazy (because I'm really weak in geometry, sighs)

Could you help me? c:

The question is as it follows:

take the segment AB with a lenght 6. Consider a semicircle with AB as the diameter. Let P be a point on the arc AB. Let x = <ABP.

1) express the area of the triangle ABP in terms of X.

2) find the range of x for which the are of the triangle

3) if the point P is so chosen that PA + PB = holds, find the area of the triangle ABP.

I don't know how to find the area in terms of X, but with this area found, I think I can manage the other questions.

Thank you c:

Offline

**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 7,651

hi romani

There's a theorem in geometry that says that if A, B and P are points on the circumference with O as the centre then angle AOB = 2 x angle APB.

So if AOB is a diameter then AOB = 180 => APB = 90

So now you can use sines and cosines to get the base and height of the triangle and hence the area.

angle properties of a circle:

http://www.mathisfunforum.com/viewtopic.php?id=17799

Bob

Children are not defined by school ...........The Fonz

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

Offline

Pages: **1**