請高手解答難題-20點架(急)

Ball

2008-07-31 12:10 am

識1-2條就可以答啦~最好答哂啦!!!!!

1. The radius of a circle is 5. The area of a sector of the circle is 2. Find the
angle of the sector which measured in radian and in degree.

2. If tan θ=-1, find all the possible values of the pair(cos θ, sin θ).

3. Given that sin(A+B)=sinAcosB+cosAsinB,
and cos(A+B)=cosAcosB-sinAsinB, express cos(θ+π/6) and sin(θ-π/3)
in terms of cosθ and sinθ.

4a. Show that if a function y=ƒ(x) is one-to-one, then ƒ(x1)=ƒ(x2) and only
if x1=x2

4b. Show that the function g(x)=x-1 is one-to-one.

回答 (1)

Hamsterfung

2008-07-31 11:07 pm

✔ 最佳答案

1)5^2* a/360=2
25a=720 ...................a=28.8
2)tanθ=-1/1 cosθ=2開方2 sinθ= -2 開方2
or
tanθ=1/ -1 cosθ= -2 開方2 sinθ=2開方2

3)cos(θ+π/6)=cosθcos丌/6 - sinθsin丌/6
=cosθ開方3 / 2 - 1/2 sinθ
sin(θ-丌/3)=1/2sinθ - 開方3/2cosθ

4) f(x1)=a...f(x2)=b because one to one....
if a=b.....x1=x2

g(a)=a-1.......g(b)=b-1....if g(a)=g(b)...a=b...so g(x)is one to one

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