The user has provided an image with handwritten mathematical problems and diagrams. The task is to extract the mathematical expressions and solve them according to the provided schema.

Решение:

Задание 1:

Дано: \( \angle AOB = 18^{\circ} \), \( \angle COB = 18^{\circ} \).

Найти: \( \angle COA \).

Решение:

1. \( \angle COA = \angle COB + \angle AOB \)
2. \( \angle COA = 18^{\circ} + 18^{\circ} = 36^{\circ} \)

Ответ: \( \angle COA = 36^{\circ} \).

Задание 2:

Дано: \( \angle AOB = 18^{\circ} \), \( \angle BOC = 18^{\circ} \), \( \angle COD = 18^{\circ} \).

Найти: \( \angle AOD \).

Решение:

1. \( \angle AOD = \angle AOB + \angle BOC + \angle COD \)
2. \( \angle AOD = 18^{\circ} + 18^{\circ} + 18^{\circ} = 54^{\circ} \)

Ответ: \( \angle AOD = 54^{\circ} \).

Задание 3 (предположительно):

Дано: \( \angle GOC = 90^{\circ} \), \( \angle GOB = 18^{\circ} \).

Найти: \( \angle BOC \).

Решение:

1. \( \angle BOC = \angle GOC - \angle GOB \)
2. \( \angle BOC = 90^{\circ} - 18^{\circ} = 72^{\circ} \)

Ответ: \( \angle BOC = 72^{\circ} \).