Question

The coordinates of the vertices of ΔMDT are M (4, −3),D (−6, −1), and T (7, −8). Identify the perimeter of ΔMDT. Round each side length to the nearest tenth before adding. I understand the formula, but appear to have miscalculated in each of my attempts.

32.4
36.9
30.8
29.1

Answer 1

`M=(4,-3)\qquad D=(-6,-1)\qquad T=(7,-8)\\\\\\ |MD|=√(\big(-6-4\big)^2+\big(-1-(-3)\big)^2)=√(\big(-10\big)^2+\big(-1+3\big)^2)=\\\\=√(100+2^2)=√(104)\approx\boxed{10.2}\\\\\\\\ |DT|=√(\big(7-(-6)\big)^2+\big(-8-(-1)\big)^2)=√(\big(7+6\big)^2+\big(-8+1\big)^2)=\\\\=√(13^2+(-7)^2)=√(169+49)=√(218)\approx\boxed{14.8}\\\\`



`|TM|=√(\big(4-7\big)^2+\big(-3-(-8)\big)^2)=√(\big(-3\big)^2+\big(-3+8\big)^2)=\\\\=√(9+5^2)=√(9+25)=√(34)\approx\boxed{5.8}`

So the perimeter:


`P_(\Delta MDT)=|MD|+|DT|+|TM|\approx10.2+14.8+5.8=\boxed{30.8}`

Answer C.