You can focus on the two sub-triangles ABC and ACD
We know that they are both right triangles, because we're given that AC and BD are perpendicular.
The sides AB and AD are the hypothenuses of these triangles, so we know their length through the pythagorean theorem:
But since we're given 
, the expressions for AD and AB are actually the same expression. This proves that AD=AB, and thus that the triangle is isosceles.
The relationship between 2/3 of 3/4 and 3/4 of 2/3 is that the product will equal the same because in multiplication, it doesn't matter what order you put the numbers in because it will equal the same product.
Tails was landed 17/25 times, so the experimental probability would be .68 or 68%
17/25 = .68
Hope this helps!
Do you mean a_(n+1), worded a sub (n+1)?
If so yes. If the function of the sequence is getting smaller or more negative with each term.
