Yahoo Answers is shutting down on May 4th, 2021 (Eastern Time) and beginning April 20th, 2021 (Eastern Time) the Yahoo Answers website will be in read-only mode. **There will be no changes to other Yahoo properties or services, or your Yahoo account.** You can find more information about the Yahoo Answers shutdown and how to download your data on this help page.

## Trending News

# maths question

1.cos30度xcos45度+sin60度xsin45度

2. cos^2 45度xsin30度

_________________

tan^2 60度

3. tan60度 = 開方8xcos45度

_______

sin(acute angle/3+35度)

4.BCDE is a triangle and ABC is a straight line. If Ad is 20cm,AE =10x開方2and ADE=60度,find the lenght of CD and cx

### 1 Answer

- 打倒美帝紙老虎Lv 61 decade agoFavorite Answer
(I omitted the degree notation)

sqrt. denotes square root.

(1)

(cos 30)(cos 45)+(sin 60)(sin 45)

=(2 sqrt.)/2[2 cos 30]

=(2 sqrt.)cos 30

=(2 sqrt.)(3 sqrt./2)

=6 sqrt./2

(2)

(cos²45)(sin 30)/tan²60

=(2 sqrt./2)²(1/2)/(3 sqrt.)²

=(1/2)(1/2)/3

=1/12

(3)

tan 60/sin (θ/3+35)=8 sqrt. cos 45

3 sqrt./sin (θ/3+35)=2(2 sqrt.)(2 sqrt.)/2

3 sqrt./sin (θ/3+35)=2

sin (θ/3+35)=3 sqrt./2

Because θ is an acute angle, therefore there is only one solution for θ/3+35

θ/3+35=60

θ/3=25

θ=75

(4)

Is there a figure?

I think it is not showing clearly.