Sum of areas of triangles
52918
Inside an equilateral triangle $ABC$,an arbitrary point $P$ is taken from which the perpendiculars $PD,PE$ and $PF$ are dropped onto the sides...
22237
Proof of triangle inequality
75356
Show that the area of a triangle is given by this determinant
94091
In $ \triangle ABC$ show that $ 1 \lt \cos A + \cos B + \cos C \le \frac 32$
8469
Dividing an equilateral triangle into N equal (possibly non-connected) parts
108274
Sum of the first $n$ triangular numbers - induction
136563
Number of triangles in a regular polygon
36442
Expected area of triangle formed by three random points inside unit circle
61270
Binomial Theorem Sum
117604
Sum of the rows of Pascal's Triangle.
93617
Sum of the product of two combinations
63314
Triangular Factorials
120215
Sum of elements of a finite field
157477
Area of a quadrilateral proof
3392
Sum of products of elements of nonempty subsets of A set
67774
Number of isosceles triangle.
15523
Graphically approximating the area under a curve as a sum of rectangular regions