Answer:
No, it is not a right triangle.
Step-by-step explanation:
The simplest way to determine is testing out the numbers with Pythagorian theorem.
If it complies with the theorem, it is a right triangle.
let's assume c = 28, b = 21, and a = 20
the longest side is the hypotenuse so side c (28 in) will be the hypotenuse.
According to the Pythagorian theorem, the square of the length of hypotenuse must equal to the sum of squares of other two sides.
check:
c^2 = 28^2 = 784
a^2 + b^2 = 21^2 + 20^2 = 841
because c^2 is not equal to a^2 + b^2, the triangle is not a right triangle.
Turn it into transcript, It's upside down and I can't see it properly.
The number that is not irrational is 
. The correct option is the second option
<h3>
Irrational numbers </h3>
From the question, we are to determine which of the given options is not irrational
Irrational numbers are the set of real numbers that cannot be expressed in the form of a fraction, p/q, where p and q are integers.
is a repeating decimal and it can be expressed as a fraction
∴ is not an irrational number. It is a rational number
The other options cannot the expressed as a fraction.
Hence, the number that is not irrational is . The correct option is the second option
Learn more on Irrational numbers here: brainly.com/question/11919233
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