# Thread: Need some Calculus Help on a few problems. (differentials)

1. ## Need some Calculus Help on a few problems. (differentials, linear approx)

I'm not entirely bright at math hehe.
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Use Differentials (or equivalently, a linear approximation) to approximate sin(25°) as follows: Let f(x) = sin(x) and find the equation of the tangent line to f(x) at a 'nice' point near 25°. Then use this to approximate sin (25°)

Approximation = _________

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Use differentials (or equivalent, a linear approximation) to approximate ln(0.97) as follows: Let f(x) = ln(x) and find the equation of the tangent line to f(x) at a 'nice' point near 0.97. Then use this to approximate ln(0.97)

Approximation = __________

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The circumference of a sphere was measured to be 90.000 cm with a possible error of 0.50000 cm. Use linear approximation to estimate the maximum error in the calculated surface area. _______

Estimate the relative error in the calculated surface area. _________

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Thanks in advance. it would be great if I can get some explanations to go with it.

Adding pictures; you dont need to do the first question. I got that one XD

2. ## Re: Need some Calculus Help on a few problems. (differentials, linear approx)

Too bad what REALLY needs to happen is for YOU to offer an explantion. If you wander off, someone will be delighted to point you in the right direction.

Let's start small. What "nice" value is there not far from 25º, such that the sine is exact?