Introduction:
A tetrahedron is a solid geometric shape with four triangular faces. When a point inside the tetrahedron is connected by straight lines to its corners, it creates several new internal planes. In this response, we will explain why the correct answer is 6.

Explanation:
To understand the number of internal planes created, let's break down the process step by step.

Step 1: Connecting the point to one corner
When the point inside the tetrahedron is connected to one of its corners, it creates a single plane. This plane is formed by the three edges connecting the point and the three vertices of the triangular face.

Step 2: Connecting the point to the second corner
Now, when the point is connected to a second corner, it creates a new plane. This plane is formed by the three edges connecting the point and the two corners, along with the two adjacent edges of the tetrahedron.

Step 3: Connecting the point to the third corner
Similarly, connecting the point to a third corner creates another new plane. This plane is formed by the three edges connecting the point and the three corners of a triangular face.

Step 4: Connecting the point to the fourth corner
Finally, connecting the point to the fourth and last corner of the tetrahedron creates another plane. This plane is formed by the three edges connecting the point and the two corners, along with the two adjacent edges of the tetrahedron (similar to step 2).

Total number of planes:
By following these steps, we have created 4 planes in total. However, there are two additional planes that are formed by the intersection of the previous planes.

Step 5: Intersection of the planes
When the planes created in steps 1 and 2 intersect, they form a new plane. This plane is formed by the intersection of two triangular planes.

Step 6: Intersection of the planes (continued)
Similarly, when the planes created in steps 3 and 4 intersect, they form another new plane. Again, this plane is formed by the intersection of two triangular planes.

Conclusion:
Therefore, by connecting a point inside a tetrahedron to its corners, we create a total of 6 new internal planes. These planes are formed by the connections made in steps 1, 2, 3, and 4, as well as the intersections of planes in steps 5 and 6.