Mathematics
State whether the following statements are true (T) or false (F):
(i) Each angle of an equilateral triangle is a right angle.
(ii) The adjacent sides of a rectangle are equal in length.
(iii) The diagonals of a rectangle are equal in length.
(iv) The diagonals of a rectangle are perpendicular to one another.
(v) The diagonals of a rhombus are equal in length.
(vi) Any three line segments make up a triangle.
(vii) All the faces of a triangular prism are triangles.
(viii) All the faces of a triangular pyramid are triangles.
Answer
(i) False
Reason — Each angle of an equilateral triangle is 60°, not 90° (right angle).
(ii) False
Reason — In a rectangle, only opposite sides are equal in length, not adjacent sides. If adjacent sides are equal, it becomes a square.
(iii) True
Reason — The diagonals of a rectangle are equal in length.
(iv) False
Reason — The diagonals of a rectangle bisect each other but are not perpendicular. They are perpendicular only in a square.
(v) False
Reason — The diagonals of a rhombus bisect each other at right angles but are generally not equal in length. They are equal only in a square.
(vi) False
Reason — Three line segments can form a triangle only if the sum of the lengths of any two sides is greater than the third side (triangle inequality).
(vii) False
Reason — A triangular prism has 2 triangular faces and 3 rectangular faces, so not all faces are triangles.
(viii) True
Reason — A triangular pyramid (tetrahedron) has 4 triangular faces — 1 triangular base and 3 triangular side faces.
Related Questions
Fill in the blanks:
(i) A cube has ….. square faces, ….. edges and ….. vertices.
(ii) A triangular prism has ….. triangular faces, ….. rectangular faces, ….. edges and ….. vertices.
(iii) A triangular pyramid has ….. faces, ….. edges and ….. vertices.
Fill in the following blanks:
(i) An angle whose measure is less than that of a right angle is …..
(ii) An angle greater than 180° and less than a complete angle is called … .
(iii) An angle whose measure is the sum of the measures of two right angles is ….. .
(iv) When the sum of measures of two angles is that of a right angle, then each one of them is …..
(v) When the sum of measures of two angles is that of a straight angle and if one of them is acute then the other is ….. .
(vi) A triangle having one of its angles as right angle and with lengths of two sides equal is called ….. triangle.
(vii) A cuboid has ….. faces, ….. edges and ….. vertices.
(viii) A rectangular pyramid has ….. faces, ….. edges and ….. vertices.
State whether the following statement is true or false. Justify your answer.
'An angle whose measure is greater than that of a right angle is obtuse'.
Comparison of lengths is possible in case of
two lines
two line segments
two rays
a ray and a line segment