You need to show us what the triangle is
Let

. Then

, and differentiating both sides with respect to

gives


Now, when

, you get

You have

, so

and

. So
Answer:

Step-by-step explanation:
1. Regroup terms.

2. Add 1 to both sides.

3. Simplify 3x + 3 + 1 to 3x + 4.

4. Subtrect 3x from both sides.

5. Simplify 4x - 3x to x.

Therefor, the answer is, x = 4.