Am I doing something wrong?

Algebra II: Equations and Triangles - Math for Morons Like Us

Scroll down the page until you hit the part that says Law of Cosines.

I have been trying to solve that problem for hours now and I don't get the same answer for Angle A.

Here is the problem. (Headbang)

--------------------------------------------------------------

**1. Problem: In ***triangle ABC*, *a = 24*,

*c = 32*, and *angle B = 115o*.

Solve the triangle.

Solution: We know two sides. Find the third

using the law of cosines.

*b2 = a2 + c2 - 2ac(cos B)*

Plug in any known information.

*b2 = 242 + 322 - 2 * 24 * 32(-.4226)*

*b2 = 2249*

Solve for *b* by taking the square

root of each side.

**b = SQRT(2249) = 47.4**

Using the law of sines,

*angle A = 27.32o*.

Since we know that triangles are made of

three angles that sum to *180o*,

we can find the measure of *angle C* by

setting up an equation.

**Angle C** = 180o - 115o - 27.32o = **37.68**

----------------------------------------------------------------

After reaching the part where is says.

Using the law of sines,

*angle A = 27.32o*.

I am unable to get angle A = 27.32 I keep getting A = 29.55

Here is the formula I keep using.

(24(Sin115))**/**(Sin(47.4)) = 29.55

I don't get how the answer is 27.32

Can anyone please tell me if I am doing something wrong or if the site is wrong...

(Special request: Does anyone know of a good site like the one I posted with step by step instructions on Trigonometry and such.(Bow))