# Thread: Construct an angle

1. ## Construct an angle

A question tells me to construct an angle using a ruler and a pair of compasses.

No idea how to do this without a protractor, any help?

2. Originally Posted by Mukilab
A question tells me to construct an angle using a ruler and a pair of compasses.

No idea how to do this without a protractor, any help?
Compass and straightedge constructions - Wikipedia, the free encyclopedia

3. Doesn't tell me how to create an angle using only a ruler and compass

4. Any other help?

I've thought about this and I don't know how it can be feasibly possible without extensive working and no calculator.

Surely there must be some error because you can simply do this with a protractor and ruler.

5. Originally Posted by Mukilab
Any other help?

I've thought about this and I don't know how it can be feasibly possible without extensive working and no calculator.

Surely there must be some error because you can simply do this with a protractor and ruler.
Isn't it amazing that the link shows a few being constructed then...

Which angle are you trying to do.

6. I have a single line. From that single line I am supposed to construct an angle of 30 degrees.

7. How to construct (draw) a 30 degree angle with compass and straightedge or ruler - Math Open Reference

Or construct a equilateral triangle using the wiki link and figure out how to divide an angle in two...

These take a bit of time to explain so google is the best bet.

8. thanks, there are so many new things on that site. I wonder how these can be proved without measurement.

9. Actually, if you want to find 30 degree angle with compass and ruler, you can do like this:
A. Draw an equilateral triangle:
Step 1: Draw a random line.
Step 2: Put the point of your compass at one end of the segment and the pencil point at the other.
Step 3: Without moving the point of the compass and without changing how wide it is set, swing the compass in approximately a quarter-circle (up & away from the line segment).
Step 4: Without changing how wide the compass is spread, move the compass point to the other end.
Step 5: Swing the compass so that the arc you are creating crosses the arc you drew in step 3.
Step 6: Mark the place where the two arcs cross.
Step 7: Using a ruler, draw line segments that connect the spot where the arcs cross to each end of the original line segment.
B. Draw a height of the triangle.