Answer:
S
ThenSn=n(a1+an)2Sn=n(a1 + an)2 , where nn is the number of terms, a1a1 is the first term and anan is the last term. The sum of the first nn terms of an arithmetic sequence is called an arithmetic series .
Step-by-step explanation:
Answer:
See below and image
Step-by-step explanation:
180 + 48 = 228
180 + 55 = 235
Answer:
3) 180°-50°=130°
4)90°-50°=40°
Step-by-step explanation:
5)angle DEC=50°(VERTICAL OPPOSITE ANGLE)
x=50°-15°=35°
6)Y+30°+50°=180°(linear pair)
Y=180°-80°
Y=100°