The angles of a quadrilateral are 110°, 72°, 55° and x°. Find the value of x.

Complete each of the following, so as to make a true statement:

(i) A quadrilateral has ________ sides.

(ii) A quadrilateral has ________angles.

(iii) A quadrilateral has ________, no three of which are ________.

(iv) A quadrilateral has ________diagonals.

(v) The number of pairs of adjacent angles of a quadrilateral is ________.

(vi) The number of pairs of opposite angles of a quadrilateral is ________.

(vii) The sum of the angles of a quadrilateral is ________.

(viii) A diagonal of a quadrilateral is a line segment that joins two ________ vertices of the quadrilateral.

(ix) The sum of the angles of a quadrilateral is ________ right angles.

(x) The measure of each angle of a convex quadrilateral is ________ 180°.

(xi) In a quadrilateral the point of intersection of the diagonals lies in ________ of the quadrilateral.

(xii) A point os in the interior of a convex quadrilateral, if it is in the ________ of its two opposite angles.

(xiii) A quadrilateral is convex if for each side, the remaining ________ lie on the same side of the line containing the side.

In Fig. 16.19, ABCD is a quadrilateral.

(i) Name a pair of adjacent sides.

(ii) Name a pair of opposite sides.

(iii) How many pairs of adjacent sides are there?

(iv) How many pairs of opposite sides are there?

(v) Name a pair of adjacent angles.

(vi) Name a pair of opposite angles.

(vii) How many pairs of adjacent angles are there?

(viii) How many pairs of opposite angles are there?

The three angles of a quadrilateral are respectively equal to 110°, 50° and 40°. Find tits fourth angle.

A quadrilateral has three acute angles each measures 80°. What is the measure of the fourth angle?