Problem 137 of 7
Correct the Pythagorean-identity error in If cos theta = 4/5, then sin^2 theta = 1 - 4/5 = 1/5.
Using a hint is okay. It just tells the trainer to give you a little more review.
Hidden until you reveal it.
catch missing square, wrong sign, invalid quadrant, or arithmetic mistake.
Hidden until you reveal it.
Bad work must contain an identity, sign, quadrant, or arithmetic mistake.
Enter your answer
Your answer is equivalent to the expected form.
Walkthrough
Full solution stays hidden until you ask for it.
1. Identify whether the error is squaring, arithmetic, or quadrant sign.
2. Apply sin^2+cos^2=1 correctly.
3. Use quadrant information for signs.
Use the worked steps, then substitute the final answer back into the original relationship to confirm it satisfies the prompt.
Vague references to trig mistakes without correcting the value or rule.