In a given Right angle triangle, Which trigonometric operation does not use the hypotenuse side?

Tan function. Suppose we have an angle ° given (Not the right angle), Tan° = Opposite/Adjacent. Sine and Cosine both use the hypotenuse in the triangle with the given angle.

How many major body systems does a human have? Name all the systems. Example: reproductive system.

There are 11 major body systems, namely : Reproductive, Immune, Integumentary, Skeletal, muscle system. Circulatory, Respiratory, Digestive, Excretory, Nervous and Endocrine System.

Suppose you are placed on a train, the train follows a straight track around the world in a straight line. The train has the ability to travel at speeds close to the speed of light. The train is now traveling close to the speed of light, whilst you are on the train. Theoretically speaking, what might happen as you approach light speed? With reference to time.

As you approach the speed of light, say 90% of the speed of light, A phenomenon of time dilation would occur for the passenger in the train, this would mean time would slow down for the traveler to compensate not passing the threshold speed of light. Resulting in say, 20 minutes passed for me, an observer watching the train and approximately 10 minutes passed for the traveler in the train, you. This is an example of the interesting results of theoretical physics and why we should continue further studying how our universe works and the laws governing it.