Where a major earthquake has happened in the past, but not in a while, is called a seismic

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Geologists know that potassium-40 decays to argon-40, with a half-life of 1.3 billion years. if an analysis of a feldspar crystal in a sample of granite shows that 75 percent of the potassium-40 atoms have decayed to form argon-40, what is the age of the granite

The european union was formally established in

In the diagram below, ab and bc are tangent to o. what is the measure of