constructing angles??

Question

i would like to know how to construct:
45 degree angles
105 degree angles
75 degree angles and
90 degree angles
can anyone please give me the rules of how to construct those angles or lead me to a website which will help me??i really need help thanks

i have to construct it not just take a protractor and draw it in but show how i got it

Answer 1

Draw a line segment AB. Put your compass point at B and stretch the compass out until it is at point A. Now draw a circle. Now move the compass point to B, leaving the compass opening the same as before and draw another circle. The circles will intersect in two points. Call them C and D. Draw CD and name its intersection with AB as the point E.

angle CEB is a right angle.

Now you need to bisect the 90 degree angle you just constructed to get two 45 degree angles. Look in your book as to how to bisect an angle.

The angle CAB = 60 degrees. So bisect it to get a 30 degree angle and then bisect it to get a 15 degree angle.

You can get a 105 degree angle by adding the 90 degree angle and the 15 degree angle.

Similarly, you can get a 75 degree angle by subtracting the 15 degree angle from 90 degrees.

Look in your book on how to copy an angle.

Answer 2

it would be easier to spend 50 cents an buy a protractor.

http://cfa-www.harvard.edu/~hrs/phys1ab/protractor.gif