The answer is: [C]: " 210 m " .
________________________________
The distance across the lake is: " 210 m " .
________________________________
Explanation: To solve:
Assume that: "L" represents the distance across the lake, in units of "m" ("meters").
We are given: "Assume the triangles are similar".
So; let us assume that: "60 m" is similar to "L" .
"x" is similar to "y" .
"20 m " is similar to "70 m".
_________________________________
So:
=
;
Note: "
=
;
Rewrite as:
=
.
Now, cross multiply:
2L = 7 * 60m ;
→ 2L = 420m ;
Divide each side of the equation by "2" ;
to isolate "L" on one side of the equation; & to solve for "L" ;
→ 2L / 2 = 420m / 2 ;
to get:
→ L = 210 m .
_______________________
The answer is: " 210 m " .
_______________________
which corresponds to:
Answer choice: [C]: " 210 m " .
_______________________