1. **Problem Statement:** Determine how many triangles are formed inside a large triangle by a vertical line from the apex to the base, two diagonals, and one horizontal segment intersecting inside. 2. **Understanding the figure:** The large triangle is divided by a vertical line from the top vertex to the base midpoint, creating two smaller triangles. 3. The two diagonals inside the large triangle intersect the vertical line and the horizontal segment, creating additional smaller triangles. 4. The horizontal segment intersects the vertical line and diagonals, further subdividing the figure. 5. **Counting triangles:** - The large triangle itself counts as 1. - The vertical line divides it into 2 triangles. - Each diagonal creates 2 more triangles on each side, adding 4. - The horizontal segment creates 3 smaller triangles inside. 6. Summing all: 1 (large) + 2 (vertical split) + 4 (diagonals) + 3 (horizontal) = 10 triangles. **Final answer:** There are **10** triangles formed inside the large triangle.