# Radians circles

1. Feb 16, 2012

### synkk

for part b i'm not sure how to do it

any hints on how to do it? Ive tried using sine rule etc but i'm just guessing, and i'm pretty sure there is a more simple method.

2. Feb 16, 2012

### Ninty64

Re: Radians/circles

Hint: What is the relation between the angles DAB and DAC?

3. Feb 16, 2012

### synkk

Re: Radians/circles

Right well I got this, i'm not sure if its right. DAB and DAC are equal so lets call DAB "a", 2pi = 2.2 + 2a so 2pi - 2.2 / 2 = a which is pi - 1.1 = 2.04?

4. Feb 16, 2012

### Ninty64

Re: Radians/circles

That's right, and I believe your math is correct too.

Since all three sides of the triangles are congruent:
$\overline{DB}\cong\overline{DC}$ given
$\overline{BA}\cong\overline{AC}$ because they are the same length
$\overline{AD}\cong\overline{AD}$ trivial, they share a common line
Then the corresponding angles in the triangles must also be congruent.

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