Mathematics
Grade 10
15 min
Construct an equilateral triangle or regular hexagon
Construct an equilateral triangle or regular hexagon
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1
Introduction & Learning Objectives
Learning Objectives
Use a compass and straightedge to construct an equilateral triangle on a given line segment.
Use a compass and straightedge to construct a regular hexagon inscribed in a given circle.
Justify the steps of a geometric construction using definitions, postulates, and theorems.
Prove that a constructed triangle is equilateral using properties of circles and congruence.
Explain the relationship between the radius of a circle and the side length of a regular hexagon inscribed within it.
Differentiate between a sketch, a drawing, and a geometric construction.
Apply construction techniques to create related geometric figures, such as a 30-60-90 triangle.
Ever wondered how ancient architects created perfectly symmetrical designs without modern tools? 🏛️ Let'...
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Key Concepts & Vocabulary
TermDefinitionExample
Geometric ConstructionThe process of drawing geometric figures using only an unmarked straightedge and a compass.Creating a perpendicular bisector of a line segment without using a protractor or ruler for measurement.
CompassA tool used to draw circles or arcs of a fixed radius. In constructions, it is used to create segments of equal length.Setting the compass to the length of segment AB to draw an arc with that radius.
StraightedgeA tool used to draw straight lines or line segments. It has no measurement markings.Connecting two points, A and B, to form the line segment AB.
Equilateral TriangleA triangle with three congruent sides and three congruent interior angles, each measuring 60°.A triangle with side lengths of 5 cm, 5 cm, and 5 cm.
Regular HexagonA polygon wi...
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Core Formulas
Equilateral Triangle Side-Angle Property
If a triangle has three congruent sides ($s_1 = s_2 = s_3$), then it has three congruent angles ($\angle_1 = \angle_2 = \angle_3 = 60^\circ$).
This is the defining property of an equilateral triangle. Our construction relies on creating three equal side lengths to guarantee the triangle is equilateral.
Inscribed Hexagon Radius Rule
The side length ($s$) of a regular hexagon inscribed in a circle is equal to the radius ($r$) of the circle. ($s = r$)
This crucial rule is the foundation for constructing a regular hexagon. By marking off chords equal to the radius around the circle, we create the six equal sides of the hexagon.
Interior Angle of a Regular Polygon
Angle = $\frac{(n-2) \times 180^\circ}{n}$, where $n$ is the number of...
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Challenging
If you construct an equilateral triangle and then construct the perpendicular bisector of one of its sides, what are the angle measures of the two new triangles formed?
A.45°, 45°, 90°
B.30°, 60°, 90°
C.60°, 60°, 60°
D.30°, 30°, 120°
Challenging
A regular hexagon is inscribed in a circle of radius 'r'. What is the length of the longest diagonal of this hexagon (one that passes through the center) in terms of 'r'?
A.r
B.2r
C.r√3
D.3r
Challenging
In the proof that a constructed triangle PQR on segment PQ is equilateral, we first establish that PR = PQ (radii of circle P) and QR = PQ (radii of circle Q). What logical property allows us to conclude that PR = QR?
A.Reflexive Property of Equality
B.Symmetric Property of Equality
C.Distributive Property
D.Transitive Property of Equality
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