Can one use "since" and "that's why" in one sentence? [closed]

Question

Is the following sentence gramatically correct? If 'no', please, give your reasons.

Since these two photos illustrate two different types of exercising that’s why I think they are good for our project.

The whole passage:

In the first photo you can see young people playing volleyball outdoors. In the second picture there is a young woman running on a treadmill in the gym. Even though they seem to be related to the topic of exercising they show different aspects of it. In the first photo there is a volleyball game which is a team sport and the second picture conveys the concept of exercising alone. Since these two photos illustrate two different types of exercising that’s why I think they are good for our project.

Answer 1

Using them together in this way is redundant. Use one or the other.

Since these two photos illustrate two different types of exercising, I think they are good for our project.

These two photos illustrate two different types of exercising. That's why I think they are good for our project.

Of these two examples, the second is more informal and better suited to speech than writing.

Also note that the noun exercise is a better fit than the verb exercising.