Tìm kiếm
Danh Vũ
3 năm trước

Cho tam giác ABC vuông tại A có
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nganna
3 năm trước

a) ^ABC=90o−^ACB=90o−48o=42o

Áp dụng hệ thức lượng vào tam giác vuông ABC ta có:

sin^ACB=ABBC

⇒AB=BC.sin^ACB=10.sin48o=7,43 cm

cos^ACB=ACBC

⇒AC=BC.cos^ACB=10.cos48o=6,69 cm

b) BE là phân giác ^ABC

⇒^ABE=^ABC2=42o2=21o

Áp dụng hệ thức lượng vào tam giác vuông ABE ta có:

cos^ABE=ABBE

⇒BE=ABcos^ABE=7,43cos21o=7,96

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