How to do more of these Pythagorean Theorem Geometry Questions?

Hi I have a few questions with these, could you please provide explanations on how to solve the questions and their answers. Thank you, if I have provided a diagram please use it to help show me! Thank you so much for the effort! Some of these questions will include bearing and 3D Pythagoras Geometry.

REVIEW SET 4A #6, 7 and 8.
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REVIEW SET 4B #6, 7, 8, and 9
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3D Pythagoras Problems 8 and 9
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1 Answer
Feb 7, 2017

See answers below

Explanation:

color(red)(4A-6)

Let Z be the point where the boat changes direction

XZY is a rignt triangle

XZ=10

ZY=10

XY^2=XZ^2+ZY^2=10^2+10^2

XY=10sqrt2

The bearing of X from Y is NW which is 90+90+90+45=315º

color(red)(4A-7)

It's the length of the longest diagonal

l=sqrt(3^2+5^2+8^2)

=sqrt(9+25+64)

=sqrt98

=9.9cm

color(red)(4A-8)

Driver A is at X after one hour (120km)

Driver B is at Y after one hour (135 km)

angle hat(XCY)=90º

The triangle CXY is rigt angle

Therefore,

XY^2=XC^2+YC^2

=120^2+135^2

XY=sqrt(120^2+135^2)

=180.6 km

color(red)(4B-6)

Angle hat(ABC)=90º

AB=27

BC=21

So,

AC^2=AB^2+BC^2

=27^2+21^2

AC=sqrt(27^2+21^2)=34.21km

color(red)(4B-7)

We have a right triangle

Distance of bottom of ladder to base of wall =x

Distance of top of ladder to the base of the wall =2x

Therefore,

15^2=x^2+(2x)^2

225=x^2+4x^2

5x^2=225

x^2=225/5=45

x=sqrt45=6.71m

Distance of top of ladder to the base of the wall =2*6.71=13.42m

color(red)(4B-8)

The longest diagonal is

sqrt(8^2+7^2+3^2)

=sqrt122=11.05m

11.05 >11

The answer is YES

color(red)(4B-9)

We have a right triangle of dimensions

10, 1 and XY

Therefore,

XY^2=10^2+1^2

=100+1=101

XY=sqrt101=10.05cm

color(red)(3D-8)

In triangle ABC

AC^2=AB^2+BC^2

AC^2=100^2+100^2=2*100^2

AC=100sqrt2

AM=1/2AC=50sqrt2

In triangle AME

ME^2=AE^2-AM^2

=100^2-2*50^2

=50^2(4-2)

=2*50^5

AE =50sqrt2=70.71

The height is =70.71m

color(red)(4B-9)

Let a=dimension of square base

The diagonal

=sqrt(a^2*a^2)=sqrt2a^2=asqrt2

Half this diagonal =1/2*asqrt2=a/sqrt2

In triangle AME

AM=a/sqrt2

AE=15

EM=10

Therefore,

AE^2=AM^2+EM^2

15^2=a^2/2+10^2

225=100+a^2/2

a^2/2=225-100=125

a^2=125*2=250

a=sqrt(250)=15.81cm

The side of the square is =15.81cm