Will mark brainliest and give 16 points! (multiple choice but try to show steps)
1.given that 0∘≤c≤180∘, determine the value(s)
of ∠c to the nearest degree when sinc=0.9848.
a) 80°, 100°
b)100°
c)10°, 80°
d)80°
2. θ is an angle in standard position whose terminal arm is in
quadrant iv and cosθ=3/sqrt(13). find cscθ.
a)−2/sqrt(13)
b)−4/sqrt(13)
c)−sqrt(13)/2
d)sqrt(13)/4
3.if secθ=−52, and sinθ> 0, what is the value of tanθ?
a) −sqrt(21)/2
b)sqrt(−21)
c)−2 sqrt(21)/21
d)−5 sqrt(21/ 21

1. The values of angle C to the nearest degree are 80° , 100° ⇒ (A)

2. csc Ф = -(√13)/2 ⇒ (C)

3. tan Ф = - (√21)/2 ⇒ (A)

Step-by-step explanation:

* Lets explain how to solve the problem

1.

∵ The measure of angle C is ⇒ 0° ≤ m∠C ≤ 180°

∴ ∠C lies in the first quadrant or in the second quadrant

∴ m∠C = Ф OR  m∠C = 180 - Ф, where Ф is an acute angle

∵ sin∠C = 0.9848

∴ sin Ф =  0.9848

- Use the inverse function sin^-1 to find Ф

∴ Ф = sin^-1 0.9848

∴ Ф ≅ 80°

- Lets find ∠C

∵ m∠C = Ф

∴ m∠C = 80°

∵ m∠C = 180° - Ф

∴ m∠C = 180 - 80 = 100°

* The values of angle C to the nearest degree are 80° , 100°

2.

- The terminal arm of angle Ф is in  quadrant IV

∵ In quadrant IV sin Ф , csc Ф , tan Ф , cot Ф are negative values

∵ In quadrant IV cos Ф , sec Ф are positive values

∵ cos Ф = 3/√13

∵ csc Ф = 1/(sin Ф)

- Lets use the identity sin²Ф + cos²Ф = 1 to find sin Ф

∵ sin²Ф + (3/√13)² = 1

∴ sin²Ф + 9/13 = 1 ⇒ subtract 9/13 from both sides

∴ sin²Ф = 4/13 ⇒ take √ for both sides

∵ sin Ф = ± 2/√13

- The value of the sin the IV quadrant is negative

∴ sin Ф = - 2/√13

∵ csc Ф = 1/sin Ф

∴ csc Ф = -(√13)/2

3.

∵ sec Ф = -5/2 and sin Ф > 0

∵ sec Ф = 1/cos Ф

- The value of cos Ф is negative and the value of sin Ф is positive,

 then Ф lies in the second quadrant

∵ In the second quadrant cos Ф , sec Ф , tan Ф , cot Ф are negative

  values but sin Ф and csc Ф are positive values

- Lets use the identity tan²Ф + 1 = sec²Ф to find tan Ф

∵ sec Ф = -5/2

∵ tan²Ф + 1 = sec²Ф

∴ tan²Ф + 1 = (-5/2)²

∴ tan²Ф + 1 = 25/4 ⇒ subtract 1 from both sides

∴ tan²Ф = 21/4 ⇒ take √ for both sides

∴ tan Ф = ± √21/2

∵ Ф lies in the second quadrant

∴ tan Ф = - (√21)/2

The answer to your question is:

Part A:  x₁ = 3   x₂ = -5/4

Part B. Vertex = (7/8, - 18.06)                                  

Step-by-step explanation:

Data

                                   4x² - 7x - 15

Part A. Factor the expression given to find the x - intercepts.

                   - Multiply 4 by -15 = -60

                   - Find the prime factors of -60

                       -60   2

                      -30    2

                     - 15     3

                       -5     5

                       -1

                    - Find to numbers that add them up give -7

                      these numbers are -12 and + 5                  

                                   4x² - 12x + 5x - 15

                                   4x(x - 3) + 5(x - 3)

                                   (x - 3)(4x + 5)

                     - Equal each term to zero to find the x-intercepts

                       x₁ = 3                x₂ = -5/4

Part B. The vertex is a minimum

                                  y =   4x² - 7x - 15

                                 y + 15 + 4(7/8)² = 4(x² - 7/4 x + (7/8)²)

                                 y + 289/16 = 4( x - 7/8)²

Vertex = (7/8, - 18.06)      

Part  C.

1.- Plot the the vertex

2.- Plot the x- intercepts

3.- Join the points