why number 8549176320 is one of a kind?

Can you find out which triangle will have a bigger area among the following?
1. A triangle with sides 300, 400 and 500
2. A triangle with sides 300, 400 and 700

Can you replace the X (both small and big x) with the numbers between 1 to 19 such that all the rows of 3 numbers between X (big x) sum to 23?

I never was there, I am always to be.
You have never ever seen me, not ever you will.
Yet I am the confidence of everyone.

Who Am I?

What is the end of everything?

Find the value of "?" in the ball picture Riddle below:

Things are just as they seem, right? Well, check again.
Can you count the number of tigers in this picture ?

Can you place six X (crosses) in below board without making three in a row in any way ?

Can you arrange four 9's and use at most 2 math symbols, to make the total 100?

You have two strings whose only known property is that when you light one end of either string it takes exactly one hour to burn. The rate at which the strings will burn is completely random and each string is different.

How do you measure 45 minutes?