Junior Cert Ordinary Constructions

The Junior Cert Ordinary course contains 13 geometry constructions.

Geometry constructions have been examined almost every year in the Junior Cert Ordinary exam.  If you are aiming for a high grade, you can’t afford to neglect this part of the course.

For general guidance on how to learn and revise constructions, click here.

Here’s the full list of JCO constructions, and the demo videos are embedded below this.

Construction 1 – Bisector of an angle, using only compass and straight edge
Construction 2 – Perpendicular bisector of a segment, using only compass and straight edge
Construction 4 – Line perpendicular to a given line l, passing through a given point on l
Construction 5 – Line parallel to given line, through a given point
Construction 6 – Division of a line segment into 2, or 3 equal segments without measuring it
Construction 8 – Line segment of a given length on a given ray
Construction 9 – Angle of a given number of degrees with a given ray as one arm
Construction 10 – Triangle, given lengths of 3 sides
Construction 11 – Triangle, given SAS data
Construction 12 – Triangle, given ASA data
Construction 13 – Right-angled triangle, given length of hypotenuse and one other side
Construction 14 – Right-angled triangle, given one side and one of the acute angles
Construction 15 – Rectangle given side lengths

See below for our demonstration videos showing you exactly how to do them.

If you need any further help or clarification, get in touch with us at any time!

All 13 Constructions for Junior Cert Ordinary Level

Full Playlist – all 13 videos on our YouTube channel

Construction 1 – Bisector of an angle, using only compass and straight edge

Construction 2 – Perpendicular bisector of a segment, using only compass and straight edge

Construction 4 – Line perpendicular to a given line l, passing through a given point on l

Construction 5 – Line parallel to given line, through a given point

Construction 6 and 7 – Division of a line into 2, 3 or any number of equal segments without measuring it [7 Not on Ordinary Level]

Construction 8 – Line segment of a given length on a given ray

Construction 9 – Angle of a given number of degrees with a given ray as one arm

Construction 10 – Triangle, given lengths of 3 sides

Construction 11 – Triangle, given SAS data

Construction 12 – Triangle, given ASA data

Construction 13 – Right-angled triangle, given length of hypotenuse and one other side

Construction 14 – Right-angled triangle, given one side and one of the acute angles

Construction 15 – Rectangle given side lengths

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