NDA | Mathematics | Properties of Triangle

If in a triangle, R and r are the circumradius and inradius respectively, then the HM of the exradii of the triangle is

If

If the sides of a triangle are 4, 5 and 8 units, then the value of the greatest angle is:

Consider a triangle ABC and let a, b and c denotes the lengths of the sides opposite to vertices A,B and C respectively. Suppose  and the area of the triangle is  , if  is obtuse and if r denotes the radius of the incircle of the triangle, then  is equal to

Consider the following statements:

1. If  is an equilateral triangle, then .

2. If ABC is a triangle in which  then

3. If ABC is any triangle, then

Which of the above statements is/are correct?