中三數學兩條【求完整說明及答案】

1) 由A點畫一條向下延伸的線,C點畫一條向左延伸的線,交點作D, ∠ADC = 90°
DC = 1800 x sin 75° - 1200 x sin 15°
AD = 1800 x cos 75° + 1200 x cos15°
tan ∠ CAD = DC/AD
∠ CAD=41.3
N41.3W



2) 63°= quadrant 1, 284°= quadrant 4
obtuse angle formed between quadrant 1 and 4,
63° + (360°-284°)= 139°

93°= quadrant 2, 348°= quadrant 4
obtuse angle formed between quadrant 2 and 4,
93° + (360°- 348°)=105°
both answers are between 90 - 180, both are obtuse angles
少作答中文題目, 希望沒有錯漏