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WAEC 2025 · Paper 1 · Q46✱✱

Without using tables, evaluate sin⁡20∘cos⁡70∘+cos⁡25∘sin⁡65∘\dfrac{\sin 20^\circ}{\cos 70^\circ} + \dfrac{\cos 25^\circ}{\sin 65^\circ}.

Worked solution (try it first)
  1. The sine of an angle equals the cosine of its complement: cos⁡70∘=sin⁡20∘\cos70^\circ = \sin20^\circ and sin⁡65∘=cos⁡25∘\sin65^\circ = \cos25^\circ.
  2. So sin⁡20∘cos⁡70∘=1\dfrac{\sin20^\circ}{\cos70^\circ} = 1 and cos⁡25∘sin⁡65∘=1\dfrac{\cos25^\circ}{\sin65^\circ} = 1.
  3. The total is 1+1=21 + 1 = 2, option A.

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