Mathematics Grade 10 15 min

Find the next shape in a repeating pattern

Find the next shape in a repeating pattern

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1

Introduction & Learning Objectives

Learning Objectives Identify the core repeating unit in a geometric pattern of congruent triangles. Describe the specific sequence of rigid transformations (translation, rotation, reflection) that generates a pattern. Use congruence postulates (SSS, SAS, ASA) to justify that shapes within a pattern are congruent. Apply algebraic rules for transformations on a coordinate plane to predict the vertices of the next triangle in a sequence. Determine the position and orientation of the nth triangle in a repeating pattern. Justify their prediction for the next shape using the precise mathematical language of geometry and transformations. Ever noticed the beautiful, repeating patterns on a tile floor or in a kaleidoscope? 💠 How do artists and designers create those perfect, endless...
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Key Concepts & Vocabulary

TermDefinitionExample Congruent TrianglesTriangles that have the exact same size and shape. All pairs of corresponding sides and corresponding angles are equal.If ΔABC ≅ ΔXYZ, it means AB = XY, BC = YZ, AC = XZ, and ∠A = ∠X, ∠B = ∠Y, ∠C = ∠Z. Rigid Transformation (Isometry)A transformation of the plane that preserves distance and angle measure. The original figure (pre-image) and the transformed figure (image) are congruent.Translations, rotations, and reflections are the three main rigid transformations. TranslationA rigid transformation that 'slides' every point of a figure the same distance in the same direction along a vector.Translating ΔABC with vertices A(1,2), B(3,1), C(2,4) by the vector <4, -1> results in ΔA'B'C' with vertices A'(5,1), B'...
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Core Formulas

Translation Rule T_{a,b}(x, y) = (x + a, y + b) Use this to find the coordinates of a point after sliding it 'a' units horizontally and 'b' units vertically. If 'a' is negative, the slide is to the left; if 'b' is negative, the slide is down. Rotation Rules (about the origin) 90° counter-clockwise: R_{90°}(x, y) = (-y, x) \\ 180°: R_{180°}(x, y) = (-x, -y) \\ 270° counter-clockwise: R_{270°}(x, y) = (y, -x) Use these rules to find the coordinates of a point after rotating it around the origin (0,0). For clockwise rotations, use the equivalent counter-clockwise rotation (e.g., 90° clockwise is 270° counter-clockwise). Reflection Rules Across x-axis: r_{x-axis}(x, y) = (x, -y) \\ Across y-axis: r_{y-axis}(x, y) = (-x, y) \\ Across...

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Sample Practice Questions

Challenging
A pattern is defined by the recursive rule: T_{n+1} is generated by applying a 180° rotation about the origin to T_n, followed by a translation T_{-2, 3}. If T1 has vertex A(4, 0), what are the coordinates of the corresponding vertex A''' on T4?
A.(4, 0)
B.(-4, 6)
C.(6, -3)
D.(-8, 9)
Challenging
A transformation maps triangle vertices (x, y) to (-y, -x). Which of the following describes this non-standard transformation?
A.270° counter-clockwise rotation about the origin.
B.reflection across the x-axis followed by a reflection across the y-axis.
C.reflection across the line y = -x.
D.180° rotation followed by a reflection across the line y=x.
Challenging
A pattern is generated by a glide reflection. Triangle 1 with vertex K(3, 2) is mapped to Triangle 2 with corresponding vertex K'( -3, 5). The transformation is a reflection across the y-axis followed by a translation. What is the translation vector?
A.<0, 3>
B.< -6, 3 >
C.<0, 7>
D.< -6, 0 >

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