Area of Triangle Small 320×275 Medium 640×549 Large 1024×879 Download Tiff Original 2400×2059 | (177.0 KB) Description "The child sees triangle ACB = triangle ADB, and that I + II = CA - DB; and so he sees that the area of triangle=1/2 area of rectangle whose base and altitude are the same as those of the triangles." -Foster, 1921 Keywords equal triangles, half base times height, rectangle, right triangles, triangle area Galleries Miscellaneous Triangles Source: Ellsworth D. Foster ed. The American Educator (vol. 1) (Chicago, IL: Ralph Durham Company, 1921)
