How to determine if an equation. is linear

The radius of the circle is 4 cm and the measure of the central angle is 90° the area of the sector with a central angle measuring 90° and radius of length 4 cm is vt cm the triangle in the sector is 4 cm the area of the triangle is v/cm² the area of the segment of the circle is (471 - ) cm?

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If sr is 4.5cm and tr is 3cm, what is the measure in degrees of angle s?