Two angles∠3 and ∠5 are each supplementary to ∠4. If m∠5 is 78°, what is m∠3?
Two angles∠3 and ∠5 are each supplementary to ∠4. If m∠5 is 78°, what is m∠3?
A) 102°
B) 2°
C) 78°
D) 90°
E) 180°
Not just according to aidan! "∠3 supplementary to ∠4" means "m∠3+ m∠4= 180" where "m" is the measure of the angle in degrees. Similarly, "∠5 supplementary to ∠4" means "m∠4+ ∠5= 180". Since those sums are both equal to 180, they are equal to each other: m∠3+ m∠4= m∠4+ m∠5. Now subtract m∠4 from both sides to get m∠4= m∠5.