Chapter 5 - Trigonometric Functions - 5.1 Angles - 5.1 Exercises - Page 503: 18

$a)1^0$ $b)91^0$

If two angles are Complement then sum of these angles is $90^0$ If two angles are Supplement then sum of these angles is $180^0$ $a)\alpha+89^0=90^0\Rightarrow \alpha =90^{0}-89^{0}=1^{0};$ $b)\theta+89^0=180^0\Rightarrow \theta=180^{0}-89^{0}=91^{0}$