They all relate to one thing

1: $$60$$ $$60$$ $$60$$
2: $$\frac{n(n+1)(2n+1)}{6}$$
3: $$\sqrt{s(s-a)(s-b)(s-c)}$$
4: $$\frac{21}{7}$$
5: 25, 36, ?
6: $$>90$$

Find what all of these mean or what they represent

(What I mean is that tell me what each of 1 to 6 is)

Hint 1:

Hint 2:

@Glorfindel got the topic right

Hint 3:

For #5, it has nothing to do with square numbers or equations relating to it

Hint 4:

Five relates to one in a way

Hint 5:

As in angles. I just picked random two numbers so that both of them added up wouldn't be greater than 179 degrees

Hint 6:

You need to find the other angle

I can link at least four to a common theme:

triangles

as follows:

1. the angles of an equilateral triangle
2. the formula for the pyramid numbers; four sides of those pyramids look like triangles
3. Heron's formula for the area of a triangle
4. a simple division yielding 3, the number of sides in a triangle
5. 49 — given 25, 36 or 49 equilateral triangles, it's possible to create another one with sides 5, 6 resp. 7 times the original (like this)
6. an obtuse triangle has an angle greater than 90 degrees

• 4 might simply be rot13(guerr fvqrf)!!
– Stiv
Mar 30 '20 at 8:40
• @Stiv could be, but why this specific numerator & denominator? Mar 30 '20 at 8:42
• 5 can be rot13(Clguntberna gurberz) or rot13(nphgr gevnatyr) Mar 30 '20 at 8:45
• About 4: Gur cv nccebkvzngvba, nygubhtu vg'f npghnyyl 22/7 Mar 30 '20 at 9:18
• @Glorfindel You got 5 wrong... I'll add a hint Apr 5 '20 at 1:05

1) 60,60,60 The sum of the three angles of any triangle in Euclidian space is 180 degrees.
2) the number of squares in a $$n*n$$ square grid
3) Heron's formula for area of triangles
4) trisection
5) 5-2=3, 6-3=3. This is the only relation I can see between 1 and 5.
6) triangle with an angle greater than 90 degrees

• For number 5 we can answer also as follows, (3^2+6^2)-(2^2+5^2)=4^2 so we have 16,25,36. Apr 5 '20 at 18:28