a. Gilligan can conclude that ΔABC ~ ΔSDC by AA similarity theorem.
b. Distance from the ship to the shore, to the nearest tenth of a foot, is: 847.8.
The AA similarity theorem states that, if two angles in one triangle are congruent to two corresponding angles in another triangle, then both triangles are similar triangles. The corresponding sides of both triangles would be proportional.
a. Triangles ABC and SDC have two pairs of congruent angles, which are:
∠SCD ≅ ∠ACB (vertical angles are congruent)
∠SDC ≅ ∠ABC (right angles = 90°)
Therefore, Gilligan can conclude that ΔABC ~ ΔSDC by AA similarity theorem.
b. Given, AB = 150 ft
BC = 23 ft
DC = 130 ft
Distance from ship to the shore = SD = ?
Thus:
AB/SD = BC/DC (proportional sides of similar triangles).
Substitute
150/SD = 23/130
SD = (130 × 150)/23
SD = 847.8 ft.
Therefore, distance from the ship to the shore, to the nearest tenth of a foot, is: 847.8.
Learn more about AA similarity theorem on:
https://brainly.com/question/2166570