Triantain

Diagram of a scalene triangle

Anns a h-uile triantan bidh na 3 ceàrnan a' dèanamh \(180^\circ\)

Diagram of a scalene triangle with angles of 70°, 50° and an unknown angle marked as x°

\[x^\circ = 180^\circ - (70^\circ + 50^\circ )\]

\[= 180^\circ - 120^\circ = 60^\circ\]

Triantan ionann-thaobhach

Ann an triantan ionann-thaobhach tha an aon fhaid anns na trì taobhan agus tha \(60^\circ\) anns gach ceàrn.

Equilateral triangle

Triantan co-chasach

Ann an triantan co-chasach tha an aon fhaid ann an dà thaobh agus tha dà cheàrn co-ionann.

Diagram of an isosceles triangle with the two equal angles highlighted

Question

Tha triantan co-chasach san diagram gu h-ìosal. Dè an luach a tha aig \(a^\circ\)?

Isosceles triangle with a 70° base angle and a vertex angle marked as a°

\[a^\circ = 180^\circ - (70^\circ + 70^\circ )\]

\[= 180^\circ - 140^\circ = 40^\circ\]