please check my answers.

Question

1.Find the area of the sector of a circle.
r=11.8cm, theta-pi/7 radians
I got 31.2cmsquared
2.Find the radius of a circle in which a central angle of pi/6radian determines a sector of area 76square meters.
I got 17.03m
3.Find the measure(in radians) of a central angle of a sector of area 45 square inches in a circle of radius 8 inches.
I need help getting the answer
4.In this question you're suppose to approximate the length by finding the necessary arc length.

A tree 520m away subtends an angle of 4degrees. find the height of the tree.
I also need help on this one
THANKS ALOT

Answer 1

1. 31.24 yes
2.17.04 yes
3. total area = pi r^2 = pi(64)
angle/2pi =45/64 pi
angle = 45/32 = 1.41 radians = 80.6 degrees
4. r = 520
circumference = 2 pi (520) = 3267
4/360 = height/3267
height = 36.3

Answer 2

Thanks so much; This was of great help!
=D