Solution to the third question: in Rt△BDE, ∵∠ BDE = 30 ∴ BD = 2be and ∵DE=30m, BD? =DE？ ﹢BE？ ∴BE= 10 radical number 3 ∴ BC = be+ 1.52 ≈ 18, and the height of 8m ∴ tree is about18.8m.

Answer to the fourth question: No ∫45? +60? ≠70? ∴ This triangle has no right angle ∴ When the 60-meter-long line segment is north-south, there is no east-west side.

Solution to question 5: I don't want to go to the map, so I understand. Expand the prism as shown in figure 1. According to Pythagorean theorem, we can get AC ′ = root sign (13? ﹢5? ) = root number 194 unfold the prism as shown in figure 2, and AC'= root number (10? +8? ) = number of roots 164÷ number of roots 194 > number of roots 164∴ number of roots 14cm with twice the shortest path.

Hope to adopt it and wish you progress in your study.