# Prove that the sum of the three angle of triangle is two right angle in a right angle triangle an acute is one fourth the other,find the acute angle.

1
by s111

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by s111

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To prove: to prove all the sum of side is 180°

construction: draw a line DE through the point A such that DE

proof

DE is parallel to BC and AC & BA are transversal

∴ ∠DAB=∠ABC

and ∠EAC =∠ACB

we know

∠DAB +∠BAC+∠EAC=180° [straight line]

we can also write that

∠ABC+∠BAC+∠ACB= 180°

Hence proved

which is equl to 2 right angle 90° + 90° = 180°

A/\q

In a right angled triangle

one angle is x

second angle is x

third angle 90°

again

90°+x + x =180°

x + + 90°= 180°

x = 75°

the second angle (acute angle)= =18.5