Maths · Geometry. The idea in plain words, the rules to remember, the mistake to avoid and a worked example, written and checked by Mega Lecture.
Geometry questions use exact words, and each word has one meaning. You must know the names of angles, triangles, quadrilaterals, polygons, solids and the parts of a circle.
Angles are named by size: acute, right, obtuse and reflex. Triangles are named by their sides: equilateral, isosceles and scalene. Quadrilaterals are named by their sides, angles and diagonals. Two shapes are congruent if they are the same shape and the same size, and similar if they are the same shape but different sizes.
In a circle, a chord joins two points on the circle, and a tangent touches the circle at one point only. For a solid, count faces, edges and vertices carefully.
Students mix up sector and segment. A sector is a slice cut by two radii, like a slice of pizza; a segment is the piece cut off by one chord.
Answer: 5 faces, 5 vertices and 8 edges
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