$\angle$1 and 72${}^{\circ }$ form a linear pair.
So, $\angle$1 + 72${}^{\circ }$ = 180°
$\Rightarrow$  $\angle$1 =  180°- 72${}^{\circ }$ 
$\Rightarrow$   $\angle$1 = 108°
Similarly, $\angle$2 and 98${}^{\circ }$ form a linear pair.
So, $\angle$2 + 98${}^{\circ }$ = 180°
$\Rightarrow$  $\angle$2 =  180°- 98${}^{\circ }$ 
$\Rightarrow$   $\angle$2 = 82°
$\therefore \angle 1+\angle 2=108°+82°=190°$

Infinite number of transversals can be drawn for any two given lines.

Angles less than 90${}^{\circ }$ are acute angles.

An obtuse angle is more than 90° but less than 180°

Angles equal to 90${}^{\circ }$ are right angles.

Parallel lines never intersect.

If three lines are cut by two transversals, then there are 6 points of intersection.

Two angles are supplementary if their sum is equal to ${180}^{\circ }$.

Each Part: 1 Mark
Sum of complementary angle is equal to ${90}^{\circ }$.
Therefore, the complement of:
(a)  ${65}^{\circ }$
      $\Rightarrow {90}^{\circ }-{65}^{\circ }={25}^{\circ }$
(b) ${32}^{\circ }$
      $\Rightarrow {90}^{\circ }-{32}^{\circ }={58}^{\circ }$

Solution: 1 Mark each
(a) Let the angle be x.
therefore its supplement  =  x  (as the supplementary angles are equal)
Sum of supplementary angles is  ${180}^{\circ }$
$x+x={180}^{\circ }$
$\Rightarrow x={90}^{\circ }$
(b) Let the angle be x.
Its supplement = 2x.
Sum of supplementary angles is  ${180}^{\circ }$
$\therefore x+2x={180}^{\circ }$
$\Rightarrow 3x={180}^{\circ }$
$\Rightarrow x={60}^{\circ }$
$\therefore$ The angle which is double its supplement = 2x = ${120}^{\circ }$

Proof: 2 Marks

$\angle 1+\angle 2+\angle 3+\angle 4={360}^0$  [Angles about a point]
$\angle 4=\angle 8$    [Pair of corresponding angles]
 
and $\angle 2=\angle 6$   [Pair of corresponding angles]
$\Rightarrow \angle 1+\angle 3+\angle 8+\angle 6={360}^0$

Each part: 1 Mark
(a) By adding consecutive triangular numbers, we get square numbers.
e.g. 1 + 3 = 4, 6 + 10 = 16, etc.
(b)  $\angle F={90}^{\circ }-{28}^{\circ }$  (Sum of complementary angles is 90${}^{\circ }$)
              $={62}^{\circ }$