It is 1.9 miles from a house to a restaurant and 1.2 miles to a pier, as shown at the right. The angle
between the two lines of sight is 87°. How far is it from
the pier across the water to the restaurant.

9514 1404 393

  2.2 miles

Step-by-step explanation:

The Law of Cosines can be used to figure this.

  c² = a² +b² -2ab·cos(C)

  c² = 1.2² +1.9² -2(1.2)(1.9)cos(87°) ≈ 4.811348

  c ≈ √4.811348 ≈ 2.193

It is about 2.2 miles across the water from the pier to the restaurant.

b) 1/3 * 1/5

step-by-step explanation:

each smallest part is 1/15 since the written one is 1/5 and it's divided by 3 equal parts. (1/5 )/3 = 1/15 = 1/3 * 1/5