Add like terms to get -4c = 3. divide by ,-4 each side so c = -3/4
Assuming you mean the central angle, semicircles have central angles of
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Answer is B. second one
A = 1/8, B = 5/16, C = 7/12, D = 5/6
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F = kq2 / r2
q = ne
F = k(ne)2 / r2
n = âš(r2F / ke2) = (r/e) âš(F/k)
k = 9 x 109 Nm2/C2
e = 1.6 x 10-19 C
n = [(4.2 x 10-10) / (1.6 x 10-19)] âš[(5.2 x 10-9) / (9 x 109)] ≅ 1.995 ≅ 2