In the given figure, AOB = 90° and ABC = 30°. Then, CAO = ?

Given: and


Construction: join CD


We know that,


AOB = 2 × ACB


90° = 2 × ACB


ACB = = 45°


Similarly,


COA = 2 × CBA


COA = 2 × 30


COA = 60°


Here,


COD + COA = AOD


COD + 60° = 180°


COD = 180° – 60° = 120°


Again


COD = 2 × CAO


CAO = = 60°


∴∠CAO = 60°

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