How do we know dinosaurs such as T-rexes actually ate meat?

You will probably say ''because of their teeth''. Pandas have the same type of sharp teeth, but they spend their whole life eating nothing but bamboo. Gorillas have sharp teeth, but they eat fruits and vegetables.

How do we know dinosaurs such as T-rexes actually ate meat?antivirus software

The fossilized intestinal content

there are bones of other animals in there.

How do we know dinosaurs such as T-rexes actually ate meat?computer virus

There has been debate about whether or not the T-Rex was a hunter or scavenger. Either one eats meat so that doesn't answer your question. The most direct proof comes from fossilized poop (coprolite). They found some in a location where the size of the poop and the time and place it was pooped out would have to have been from a T-Rex. If you wish to investigate further I will place a link below. Within the poop was found bone from a chewed up critter like a triceratops.

The reason other animals have sharp teeth is for tearing apart the plants they eat. Bamboo takes some real work to get to the good stuff. Gorillas also like to eat the inside of plants. Because of the size of the T-Rex's olfactory system it would have been able to smell things like meat from quite a distance. The teeth of a T-Rex had different rows so that when a tooth is lost there is one behind it to replace it. That type of system is only found in carivores.
I suppose you suppose T-Rex ate pasta instead of salad or meat.