=2. .SIN .COSAH AB AC B B⇒ = =4 2 2 2 2 2 2 2 2. .SIN .COS . .SIN .COS...

7) - OANH VŨ DU AN HINH 9 NHIEU CAU HOI HK1
OANH VŨ DU AN HINH 9 NHIEU CAU HOI HK1

7)

Ta có:

=

2

. .sin .cosAH AB AC B B⇒ = =

4

2

2

2

2

2

2

2

2

. .sin .cos . .sin .cosAH AB AC B B AB AC C C