Which of the following is correct set notation?
(1,2,3)
1,2,3
{1,2,3}
none of the above

 The correct option is

(C) {1, 2, 3}.

Step-by-step explanation:  We are given to select the correct set notation from the following options :

Option (A) :  The given notation is (1, 2, 3).

Here, the elements are enclosed within first brackets, which is not used to write a set.

So, this option is NOT correct.

Option (B) :  The given notation is 1, 2, 3.

Here, the elements are not enclosed within any brackets. And, the elements of a set is always written within curly brackets.

So, this option is NOT correct.

Option (A) :  The given notation is {1, 2, 3}.

Here, the elements are enclosed within curly brackets, separated by comma. Since this method is used while writing a set, so, this option is CORRECT.

Thus, (C) is the correct option.

c.   x=2.4cm

step-by-step explanation:

similar triangles are triangles which have the same shape but not the same size. this means their angle measures are equal but their side lengths are not instead they are proportional. to solve, we will set up a proportion and solve.

a proportion is two equal ratios set equal to each other. we form the ratios by finding corresponding sides (sides which match to each other on both triangles by their position). out ratios will be one side of the small triangle over the corresponding side on the big triangle as shown below:

.

to solve the proportion, we'll cross multiply by multiplying numerator with denominator across the equal sign.

hard

step-by-step explanation: