Which trigonometric identity is correct for all real where functions are defined?
Answer and explanation
Correct answer: A.
.
- Step 1: Start with the fundamental Pythagorean identity: .
- Step 2: Divide every term by :
Answer
.
Why not the others: '' has the wrong sign for 1; '' confuses with ; '' has a minus sign instead of a plus sign (in fact ).
Practise more Trigonometry, Vectors and Complex Numbers.
Free questions with an explanation for every one, and full timed EmSAT Achieve (UAE) mock tests.