4.if cotθ� = -√15/7 , use the fundamental identities to find cosθ� > 0

Question

9.A projectile is fired with an initial velocity of 88 ft/sec at an angle of 35° to the horizontal. Neglecting air resistance, what is the time of impact? (Round to the nearest tenth of a second.)
Remember: x = (v↧0cosθ�)t and y = h↧0+ (v↧0sinθ�)t – 16t^2

Answer 1

4.
√(15+49) = 8, so cosθ = 7/8

9.
we want when y=0
y = 88sin35° t - 16t^2
y=0 when t = 88sin35°/32 = 1.57

so, t = 1.6 sec

Answer 2

The answer for number 4 is wrong, Cotangent means adj/opp so it would be -15/8