How can you make number one disappear by adding something to it?

In the image given, you can find several triangles. Can you count them all?

I have nine bottles of wine and one of the nine bottles is poisoned.
I need to find the poisoned bottle with two facts
(1) Poison is deadly, only a sip will cost death
(2) I have two mice to do so.

How should I do it?

I have cities, but no houses. I have mountains, but no trees. I have water, but no fish. What am I?

What can you catch but never throw?

If six children and two dogs were under an umbrella, how come none of them got wet?

We know that the number 7 is the prime followed by a cube. Which next number is also a prime followed by a cube?

If you go to the movies and you're paying, is it cheaper to take one friend to the movies twice, or two friends to the movies at the same time?

A lion and its tamer are standing inside a cage that measures 1 unit in radius. Both of them can effortlessly run at the speed of 1 unit maximum.

1) Suppose the lion is hungry, will he be able to eat up the tamer?
2) If yes, how long can the tamer survive?

Can you decipher the below rebus?

PBLUESAISNUERSES