Check the picture below.
we know that the arcST is 30°, meaning the inscribed angle intercepting it will be half that or 15°.
in the triangle RWT, two sides of it are RT and RW, both of which are radius segments and thus equal, meaning that triangle RWT is an isosceles, and in an isosceles the twin sides also make twin angles, meaning that ∡RTW is a twin of the inscribed angle ∡RWT.
To get to 86 by only using 10's and 1's you count by 10, 8 times and count by 1, 6 times.
1) The perimeter is the sum of the lengths of the straight edge (the diameter of the semicircle) and the length of the arc of the semicircle.
The circumference of a 4 ft circle is
π*diameter = π*4 ft ≈ 12.566 ft
The semicircle will have a length that is half that, 6.283 ft. When this length is added to the diameter, the perimeter is found to be
Perimeter = 4 ft + 6.283 ft ≈ 10.3 ft.
2) The area of a circle is given by the formula
A = (π/4)d²
For a diameter of 15 inches, the area is
A = (π/4)(15 in)² = 56.25π in²
A ≈ 176.7146 in²
The area of the circle is about 176.71 in².
Chance of boy: 627/1,358
Chance of girl: 731/1,358
