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dalvyx [7]
2 years ago
8

Suppose sin(A) = 1/4. use the trig identity sin^2(A)+cos^2(A)=1 to find cos(A) in quadrant II. around to ten-thousandth.

Mathematics
1 answer:
larisa86 [58]2 years ago
8 0

In quadrant II, \cos(A) will be negative. So

\sin^2(A) + \cos^2(A) = 1 \implies \cos(A) = -\sqrt{1 - \sin^2(A)} = -\dfrac{\sqrt{15}}4 \approx \boxed{-0.9682}

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What you have to do is take one of these and sort it out to an identity you know is true, or...

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Next is b. Here we have (cscx + cotx)² = 1. Let's take the square root of each side...cscx + cotx = 1. Now you should be able to see why this can't work as a Pythagorean Identity. There's always that test we can do for verification...5/3 + 3/4 ≠ 1, nor is (5/3 +  3/4)².

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(256/144) = (256/144)
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