Based on the reading, what are the properties of carbon-14? Check all that apply.
Carbon-14 is a naturally occurring carbon isotope.
Carbon-14 has a known half-life.
Carbon-14 decays completely within 1,000 years.
Carbon-14 is not radioactive.
Carbon-14 is present in all living organisms.

This is so hard and it’s for a test

Can somebody 1. what is the formula for finding the vertical distance between two points on a coordinate plane?

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.