Mathematics
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'.
Lines & Angles
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Answer
False
Justification — An angle greater than a right angle (90°) need not be an obtuse angle. An obtuse angle lies strictly between 90° and 180°. Angles greater than 90° also include:
Straight angle (exactly 180°)
Reflex angle (between 180° and 360°)
Complete angle (exactly 360°)
For example, 200° is greater than 90° but it is a reflex angle, not an obtuse angle.
∴ The given statement is false.
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Related Questions
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 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.
Comparison of lengths is possible in case of
two lines
two line segments
two rays
a ray and a line segment
A reflex angle measures
more than 90° but less than 180°
more than 180° but less than 270°
more than 180° but less than 360°
none of these