Question

why is a concave mirror is called as converging mirror?

Answer 1

because when ray of light come from infinity they converge/meet at focus
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Answer 2

In concave mirror the rays coming, are reflected inwardly and thus meet at a point in the principle axis..

This appears such that the rays are converging, irrespective of divergence that convex mirrors do.

These rays are converged due to the shape and radius of curvature of the mirror.
Thus concave mirrors are called converging mirrors.
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