ABCD is a rhombus and P, Q, R and S are the mid-points of the sides AB, BC, CD and DA respectively. Show that the quadrilateral PQRS is a rectangle.
In ΔABC, P and Q are the mid-points of sides AB and BC respectively.
∠ PQ || AC and PQ = \(\frac{1}{2}\)
AC (Using mid-point theorem) ... (1)
In ΔADC,
R and S are the mid-points of CD and AD respectively.
∠RS || AC and RS = \(\frac{1}{2}\) AC (Using mid-point theorem) ... (2)
From Equations (1) and (2), we obtain
PQ || RS and PQ = RS
Since in quadrilateral PQRS, one pair of opposite sides is equal and parallel to each other, it is a parallelogram.
Let the diagonals of rhombus ABCD intersect each other at point O.
In quadrilateral ∠OMQN,
MQ || ON ∠( PQ || AC) QN || OM ( QR || BD)
Therefore, OMQN is a parallelogram.
∠MQN = ∠NOM
∠PQR = ∠NOM
However, ∠NOM = 90° (Diagonals of a rhombus are perpendicular to each other) ∠PQR = 90°
Clearly, PQRS is a parallelogram having one of its interior angles as 90º.
Hence, PQRS is a rectangle.
Use these adverbs to fill in the blanks in the sentences below.
awfully sorrowfully completely loftily carefully differently quickly nonchalantly
(i) The report must be read ________ so that performance can be improved.
(ii) At the interview, Sameer answered our questions _________, shrugging his shoulders.
(iii) We all behave _________ when we are tired or hungry.
(iv) The teacher shook her head ________ when Ravi lied to her.
(v) I ________ forgot about it.
(vi) When I complimented Revathi on her success, she just smiled ________ and turned away.
(vii) The President of the Company is ________ busy and will not be able to meet you.
(viii) I finished my work ________ so that I could go out to play