Saturday, March 21, 2009

Questions cosθ sin θ sinθ - cosθ

  • Solve x = log[3] 81 + log[3]1/9

For what value of x, the following matrix is singular ?
(5-x) (x + 1)

(2) ( 4)

3.. The matrix A =

3 2 satisfies the relation A2 - 4A + I = 0. Find A-1.
1 1

4. cosθ sin θ sinθ - cosθ
Simpliy cosθ + sinθ
- sinθ cosθ cosθ sinθ

5. Evaluate

-1
∫ 1/x dx
-4

6. A wire of length 28m is to be cut into two pieces. One of the pieces is to be made into a square and the other into a circle. What should be the length of the two pieces so that the combined area of the square and the circle is minimum?

7. A window is in the form of a rectangle surmounted by a semi-circular opening.
The total perimeter of the window is 10m. Find the dimensions of the window to
admit maximum light through the whole opening

8. A square piece of tin of side 48 cm is to be made into a box without top, by cutting a square from each corner and folding up the flaps to form the box. What should be the side of the square to be cut off, so that the volume of the box is the maximum possible? Also find the maximum volume.

11 comments:

  1. Solve x = log[3] 81 + log[3]1/9

    x= log[3] (81*1/9)

    x= log[3] 9

    x= log9/log 3

    x= 2

    ReplyDelete
  2. for singular matricies major- minor = 0

    ReplyDelete
  3. miss i dont understand, please help, if u say Simpliy cosθ + sinθ
    since cosθ = -sinθ
    and sinθ= cosθ
    then cosθ + sinθ simplifies to be
    -sinθ+cosθ
    i not sure if that rite

    ReplyDelete
  4. using the technique i used b4 to simpliy - sinθ cosθ cosθ sinθ

    since cosθ = -sinθ
    and sinθ= cosθ
    then - sinθ cosθ cosθ sinθ
    equals cosθ- sinθ - sinθ cosθ
    these not looking rite, i dont think this is the wway to simplify the question, sum1 please help

    ReplyDelete
  5. when evaluating -1
    is equal to -1x since if u diff. -1x u get -1, i ent sure, please help sum1

    ReplyDelete
  6. when evaluating ∫ 1/x dx
    u increse the power by 1
    so u get 1 cuz 1/x*by x = 1
    where i dont understand, cuz the next step is to divide the co-effecient by the power and there is no power so i gues u get 0, i lost with this step so please help.

    ReplyDelete
  7. Q1

    Solve x = log[3] 81 + log[3]1/9
    rule: loga + log b = log ab

    so, x= log[3] (81*1/9)

    x= log[3] 9
    rule: log mv = log m / logv
    so, x= log9/log 3

    hence, x= 2

    ReplyDelete
  8. well ram i'm kinda confused too but i think u were rite with d 1st sin cos question, as for d other 1 with
    - sinθ cosθ cosθ sinθ
    equals cosθ- sinθ - sinθ cosθ
    i was wondering if we can further simplify it as

    -2sin@ + 2cos@

    i'm not sure!

    ReplyDelete
  9. Q5. Evaluate

    -1
    ∫ 1/x .dx
    -4


    -1
    ∫ x^-1 .dx
    -4 since -1 + 1 = 0 we get...

    -1
    ∫ 1/0 x^0 .dx
    -4


    -1
    ∫ 1 + c
    -4

    this is my answer...not sure if its correct though..any ideas anyone?

    ReplyDelete
  10. attempting Q8. lol

    v = sxsxs or s^3
    s = 48 - 2x
    so, v = (48 - 2x)^3

    v = (2340 -192x +4x^2)(48 -2x)
    v = 110592 - 13824x + 576x^2 -8x^3

    this is a strange answer!

    ReplyDelete
  11. anyone wants to try Q6 and Q7 i dont kno how to start! help!

    ReplyDelete