From Gogeometry Using Pythagoras central and inscribed angle Equilateral triangle DC=DA and ∠ADC= π/3 => ΔADC is equilateral∠CAD= π/3, ∠BAC+∠CAD=∠BAD=75° => ∠BAC=15°∠ACD= π/3, ∠BCA+∠ACD=∠BCD=155° => ∠BCA=75°∠BAC=15° et ∠BCA=75° => ∠ABC= π/2 ΔADC is equilateral and EC=ED => ∠AEC= π/2∠ABC= π/2 et ∠AEC= π/2 => A, B, C and E are […]

Gogeometry Problem 405

The quadrilateral ABCD is a parallelogram <=> Two pairs of opposite sides are parallel <=> Two pairs of opposite sides are equal <=> Two pairs of opposite angles are equal <=> Adjacent angles are supplementary <=> The diagonals bisect each other <=> One pair of opposite sides is parallel and […]