Can someone please answer?

Which theorem is it?

9514 1404 393

  HL

Step-by-step explanation:

The triangles are right triangles, opening the possibility of using the special right-triangle congruence theorems.

The hypotenuses are marked congruent, and one leg is shared. No angles (except the right angle) are marked congruent. With only two sides and one angle, the AAS, SSS, and ASA theorems cannot apply.

The HL theorem can be used to show the triangles are congruent.

, and

for

step-by-step explanation:

we can analyze the pattern at which the terms increase. let us denote , , , so that we can call

note the following:

the pattern: to get the next term value, we just add the next term number (e.g. 1st, 2nd, to the previous term value (term values are the given numbers in the question, 1, 3, 6, 10, 15,

from , to get to , we add

from , to get to , we add

etc.

we need to form a recursive formula, a formula that has the next term as a function of the previous term. so a possible recursive formula can be

, and for