15. (01.01) What is the value of the radius of the following circle with an area of 154 cm2? (1 point)
Area

154 cm^2

*4.9 cm
*7.0 cm
*25 cm
*68 cm

Could someone with number 1 and 2

The position of a moving particle is given by the position function: f(t)=-9t-t^2-0.2t^3+0.1t^4 0 a. at what time does the particle reverse direction? b. when is the displacement positive? (round one decimal place and answer in interval notation) c. when is the displacement negative? (round one decimal place and answer in interval notation) d. when is the particle’s acceleration positive? (round one decimal place and answer in interval notation) e. when is the particle’s acceleration negative? (round one decimal place and answer in interval notation)

If the value of cos330°is√3/2 then find cos 165°.