Question

half of a circle is known as a
an is a part of the circumference of a circle.
the mathematical constant approximately equal to 3.14159, which is crucial for calculating circle properties, is
the formula for calculating the length of an arc, given the central angle in degrees, is arc length = 2πr(θ/360), where \θ\ represents the angle.

Explanation:

• For the first blank, by the definition of a semicircle, half of a circle is called a semicircle.
• For the second blank, according to the definition of an arc, a part of the circumference of a circle is an arc.
• For the third blank, based on the knowledge of mathematical constants, the constant approximately equal to 3.14159 for circle - related calculations is pi ($\pi$).
• For the fourth blank, in the arc - length formula \(s = 2\pi r(\theta/360)\) (where \(s\) is the arc length and \(r\) is the radius), \(\theta\) represents the central angle.

Answer:

semicircle, arc, pi ($\pi$), central