Toán Lớp 9: Giải tam giác ABC vuông tại A
a,AC=10cm
BC=15cm
b,AB=10cm
Góc C=45°
c,AB=5cm
Góc C=28°
d,AB=7cm
AC=12cm
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Toán Lớp 9: Giải tam giác ABC vuông tại A
a,AC=10cm
BC=15cm
b,AB=10cm
Góc C=45°
c,AB=5cm
Góc C=28°
d,AB=7cm
AC=12cm
Comments ( 1 )
=>AB=sin30.AC=5cm
=>BC²=AC²+AB²=125=>BC=√125=5
b. tanα=AB/AC
=>AC=AB/tanα=10/1=10cm
=>BC²=AC²+AB²=200=> BC=√200
c. cosα=AB/BC
=>AB=BC.cosα=20.0,8=16cm
=>AC²=BC²-AB²=> AC=12cm
d. BC²=AC²+AB²
cp1 AC=18,AB=21
=>BC²=18²+21²=>BC=3√85