What is the exact value of the trigonometric function cos(-870)?

What is the vertex form of f(x) = x2 + 6x + 3

Use the data on the dot plot to answer the question.how many people read for more than three hours last week? i'm on a unit test review

If m∠abc = 70°, what is m∠abd? justify your reasoning.  using the addition property of equality, 40 + 70 = 110, so m∠abd = 110°.  using the subtraction property of equality, 70 − 30 = 40, so m∠abd = 30°.  using the angle addition postulate, 40 + m∠abd = 70. so, m∠abd = 30° using the subtraction property of equality.  using the angle addition postulate, 40 + 70 = m∠abd. so, m∠abd = 110° using the addition property of equality.