- #1
DieCommie
- 157
- 0
Hello,
I am finished with Calc III and now am in a Mathmatical Methods course. For the first day we were given a "Prerequisites Inventory", basically problems we should know. But I can't do most of them!
If you can help me with any I would appreciate it.
#4 If cos(24) (degrees) = 0.913, sin (24) = 0.407, cos(17) = 0.956 and sin (17) = 0.292 then what is cos (41)? Do not use a calculator.
#4 Obviously 24+17 = 41, but I know that Cos(24) + cos(17) is not equal to cos(41).
#6 Compute each of the following to 4 or 5 place accuracy as easily as you can without using a calculator or computer: (You should be able to do them in your head)
(b) [tex]/sqrt{0.9997} [/tex]
(d) cos(0.025) radians
(e) ln(1.0001)
(f) [tex] a^2 - b^2 [/tex], where a = 1.2543 and b = 1.2539
(b) I know that the answer is going to be inbetween 1 and .09997, but I don't know how to get 4 to 5 digits of accuracy in my head.
(d) I know that sin of a small angle can be approximated by that angle, but is there a similar rule for cosine? I thought maybe I can approximate the cos of a small angle by 1-(small angle), but that does not work.
(e) Again, I know the ballpark (very close to zero, because ln(1) = 0), but I don't know how to get 4 to 5 digits of accuracy in my head.
(f) Here I know that it could be represented by (a+b)(a-b). But I can't seem to do that in my head...
#9 Compute the derivative of [tex] f(x) = x ln (\frac{x}{x^2 + a^2})[/tex]
This derivative I can calculate on paper, but I can't do it quickly. In fact it took me quite a long time. The assignment says should be able to do in about 30mins, which makes me thinkg there must be some trick or mental algorithm or something to do it quickly.
There are many other problems like this that I am struggling with. But they all have a similar theme, a problem I should be able to do in my head or at least without a calculator.
I have never been good at math, but this assignment makes me feel real stupid. Any suggestions on how to approach these would be helpful.
Thank you
I am finished with Calc III and now am in a Mathmatical Methods course. For the first day we were given a "Prerequisites Inventory", basically problems we should know. But I can't do most of them!
If you can help me with any I would appreciate it.
Homework Statement
#4 If cos(24) (degrees) = 0.913, sin (24) = 0.407, cos(17) = 0.956 and sin (17) = 0.292 then what is cos (41)? Do not use a calculator.
Homework Equations
The Attempt at a Solution
#4 Obviously 24+17 = 41, but I know that Cos(24) + cos(17) is not equal to cos(41).
Homework Statement
#6 Compute each of the following to 4 or 5 place accuracy as easily as you can without using a calculator or computer: (You should be able to do them in your head)
(b) [tex]/sqrt{0.9997} [/tex]
(d) cos(0.025) radians
(e) ln(1.0001)
(f) [tex] a^2 - b^2 [/tex], where a = 1.2543 and b = 1.2539
Homework Equations
The Attempt at a Solution
(b) I know that the answer is going to be inbetween 1 and .09997, but I don't know how to get 4 to 5 digits of accuracy in my head.
(d) I know that sin of a small angle can be approximated by that angle, but is there a similar rule for cosine? I thought maybe I can approximate the cos of a small angle by 1-(small angle), but that does not work.
(e) Again, I know the ballpark (very close to zero, because ln(1) = 0), but I don't know how to get 4 to 5 digits of accuracy in my head.
(f) Here I know that it could be represented by (a+b)(a-b). But I can't seem to do that in my head...
Homework Statement
#9 Compute the derivative of [tex] f(x) = x ln (\frac{x}{x^2 + a^2})[/tex]
Homework Equations
The Attempt at a Solution
This derivative I can calculate on paper, but I can't do it quickly. In fact it took me quite a long time. The assignment says should be able to do in about 30mins, which makes me thinkg there must be some trick or mental algorithm or something to do it quickly.
There are many other problems like this that I am struggling with. But they all have a similar theme, a problem I should be able to do in my head or at least without a calculator.
I have never been good at math, but this assignment makes me feel real stupid. Any suggestions on how to approach these would be helpful.
Thank you