what is the missing justification in the proof of the Pythagorean identity, sin^2x+cos^2x=1 using a right triangle?

Answer:
The justification that is missing in the following table is:
option: D Pythagorean Theorem
Step-by-step explanation:
Pythagorean Theorem states that in a right angled triangle if , 'a' is the perpendicular side, 'b' is the base and 'c' is the hypotenuse then:
a²+b²=c²
Hence, the justification that is missing in the following proof is the use of Pythagorean Theorem as is stated above.
Hence, option: D is the correct answer to this question.