Chiều cao là:
17,2 x 2 : 4 = 8,6 (cm)
Diện tích hình tam giác là:
12,5 x 8,6 : 2 = 53,75 (cm2)
Đáp số: 53,75cm2
Chiều cao hinh tam giac la : 17,2 x 2 : 4 = 8,6 (cm)
Diện tích hinh tam giac la: 12,5 x 8,6 : 2 = 53,75 (cm2)
Đáp số : 53,75 cm vuong
Độ dài đáy mới :
12,5 + 4 = 16,5 ( cm )
\(ax4:2=17,5\left(cm^2\right)\)Stam giác = \(\frac{axh}{2}\)
Ta có :
\(\frac{ax16,5}{2}-\frac{ax12,5}{2}=17,2\left(cm^2\right)\)
\(ax\left(16,5-12,5\right):2=17,5\left(cm^2\right)\)
\(ax4:2=17,5\left(cm^2\right)\)
\(ax2=17,5\left(cm^2\right)\)
a = 17,5 : 2 = 8,75 ( cm2 )
Diện tích tam giác đã cho :
8,75 x 12,5 : 2 = 54,6875 ( cm2 )
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