How to work out the decimal between 2.65 and 2.66? with working out

-- There are an infinite number of different numbers between 2.65 and 2.66 .
To create one, just write ' 2.65 ' and add any quantity of any digits you want
after the ' 5 '.

--  If you want the number that's exactly in the middle between them, then
that's just the average of the two numbers.

The average of any two numbers is    (1/2) x (the sum of the numbers).

       (1/2) (2.65 + 2.66) = (1/2) (5.31)   =   2.655 .   

Okay so for every triangle has three angles that always add up to 180 degrees. and to tell the difference between whether they are secure, right or obtuse is that acute: has one angle that is less than 90 degrees. right triangle means there is at least one angle that is exactly 90 degrees. and an obtuse angle has an angle that is bigger than 180 degrees. i’ll do #13 as an example: 13. 40 and 50 so if every triangle has 180 degrees 40+50= 90 degrees then180-90= 90 degrees so the third angle is 90 degrees and because this triangle has a 90 degree angle it means it is a right triangle