## Trigonometry 7th Edition

$90^{\circ}$ is neither acute nor obtuse angle. It is a right angle. Complement of $90^{\circ}$ = $0^{\circ}$ Supplement of $90^{\circ}$ = $90^{\circ}$
$90^{\circ}$ is a right angle as angles that measure $90°$ are called right angles. Complement of $90^{\circ}$ = $90^{\circ} - 90^{\circ}$ = $0^{\circ}$ (As sum of the measures of complementary angles is 90 degrees, we can find 'one' by subtracting 'other' from $90^{\circ}$ ) Supplement of $90^{\circ}$ = $180^{\circ} - 90^{\circ}$ = $90^{\circ}$ (As sum of the measures of supplementary angles is 180 degrees, we can find 'one' by subtracting 'other' from $180^{\circ}$)