Page 40 - Engineering
P. 40
ﺍﳌﺴﺘﻘﻴﻤﺎﺕ ﻭﺍﻟﺰﻭﺍﻳﺎ ٢٧
F
E
G
25°
BD
A
)د( 45° C )ب( 55° )أ( 65°
)ج( 50°
اﻟﺤﻞ :اﻹﺟﺎﺑﺔ ﻫﻲ )أ( :ﲟﺎ أن DBF = 90°ﻓﺈن .EBF = 90° − 25° = 65°
إذن ABC = EBF = 65° ،ﺑﺎﻟﺘﻘﺎﺑﻞ ﺑﺎﻟﺮأس.
) (٩ﻣﺎ ﻗﻴﺎس اﻟﺰاوﻳﺔ yﰲ اﻟﺸﻜﻞ اﳌﺮﻓﻖ؟
2x + 5
y
8x − 5
)د( 50° )ج( 41° )ب( 30° )أ( 21°
اﻟﺤﻞ :اﻹﺟﺎﺑﺔ ﻫﻲ )ج( :ﻟﺪﻳﻨﺎ
ﺑﺎﻟﺘﻨﺎﻇﺮ y = 2x + 5°
زاوﻳﺔ ﻣﺴﺘﻘﻴﻤﺔ. y + 8x − 5° = 180°
ﻣﻦ ذﻟﻚ ﻧﺮى أن y = 2x + 5°و .y = −8x + 185°وﻟﺬا ﻓﺈن
2x + 5° = −8x + 185°
10x = 180°
x = 18°
وﺑﺎﻟﺘﺎﱄ ﻓﺈن .y = 2x + 5° = 2 ×18° + 5° = 41°
