Triangle ABC is similar to triangle DEF. 15 cm
5 cm
4 cm
B 3 cm C
E
9 cm
F
Which proportion can be used to find the length of DE in centimeters?
OR -

the answer is a

step-by-step explanation:

because if you put 1 in to the square root of x it equals 300.

, 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