c. Given angle ABC has angle bisector BD, where AB = CB, find the value of x if AD = 5x + 10 and DC = 28 - x.

Do I just set them equal to each other ?

I mean isoceles

To find the value of x, you need to set the length of AD equal to the length of DC, since BD is an angle bisector.

So, you can set up the equation:

5x + 10 = 28 - x

Now, you can solve this equation for x.

Start by adding x to both sides:

5x + x + 10 = 28 - x + x

This simplifies to:

6x + 10 = 28

Next, subtract 10 from both sides:

6x + 10 - 10 = 28 - 10

This simplifies to:

6x = 18

Finally, divide both sides of the equation by 6 to solve for x:

6x/6 = 18/6

This gives you:

x = 3

Therefore, the value of x is 3.

To solve this problem, you need to use the angle bisector theorem, which states that if a ray bisects an angle of a triangle, then it divides the opposite side into two segments that are proportional to the other two sides of the triangle.

In this case, you have angle ABC with angle bisector BD, where AB = CB. Let's call the length of AD as 'a' and DC as 'b'.

According to the angle bisector theorem, we have:

AD / DC = AB / CB

Plug in the given values:

(a) / (b) = (AB) / (CB)

Since AB = CB, we can substitute the value:

(a) / (b) = 1

Now we can work with the given information: AD = 5x + 10 and DC = 28 - x.

Substituting these values into our equation, we get:

(5x + 10) / (28 - x) = 1

Now you can solve this equation for the value of x by cross-multiplying:

5x + 10 = 28 - x

Combine like terms:

6x + 10 = 28

Subtract 10 from both sides:

6x = 18

Divide by 6:

x = 3

Therefore, the value of x is 3.

yes,

ABC is equilateral
angles at D are right angles
so ABD = CBD
CDB is congruent to ADB
AD = DC