# Find an angle

• Mar 16th 2010, 11:06 AM
gracey
Find an angle
Hey

I'm trying to find angle g and am completely stuck.
Any help would be awesome thanks

gracey x
• Mar 16th 2010, 01:28 PM
Soroban
Hello, gracey!

You left out something in the diagram.
I'll take a guess at what you meant.

Given: .\$\displaystyle \angle A = 43^o,\;AB = BC,\;{\color{blue}CD = DE}\;\;{\color{red}?}\$

Find: .\$\displaystyle \angle g\$

Code:

```                B                 o               *  *             *      *           *          *         * 43°      43° *     A o  *  *  *  *  o  *  *  *  o E                           C * 43°    g  *                               *      *                                 *  *                                   o                                   D```

Since \$\displaystyle \Delta ABC\$ is isoscles: .\$\displaystyle \angle BCA \,=\,\angle A \,=\,43^o\$

Since \$\displaystyle \angle BCA\$ and \$\displaystyle \angle ECD\$ are vertical angles: .\$\displaystyle \angle ECD \,=\,43^o\$

Since \$\displaystyle \Delta CDE\$ is isosceles: .\$\displaystyle \angle g \,=\,\angle ECD \,=\,43^o\$