If ∠a = 35°, what does ∠b equal?
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These are complementary angles.
If two angles are complementary, then
the sum of their measures is 90°.
Since we know that one of the angles measures 35°, we can find the measure of the other by taking 90 minus the measure of the original angle which in this case is 90 - 35.
So we have 90° - 35° which is 55°
So the measure of the other angle is 55°