Can someone please help me with my homework

Do not use, there's still one more piece of the puzzle missing.

X =

Step-by-step explanation:

Lets look everything over and compare the corresponding parts of the 2 triangles.

One side of each is shared between the two triangles.

Another side of each triangle is 13 on each triangle.

The included angle of one triangle is 80 degrees and the other is 110 degrees.

, 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