Step-by-step explanation:
sum of the arithmetic sequence
a1 = 8
a2 = a1 + 8 = 8+8 = 16
...
an = 8×n
the sum of the first n elements of such a series is
n/2 × (2×a1 + (n - 1)×d]
with d being the difference between 2 consecutive elements (= the added constant).
so,
s30 = 30/2 × (2×8 + 29×8) = 15×(31×8) = 3720
The middle point of BC is (0,2), the midpoint of CD is (1,0)
to prove two lines are parallel, prove their slopes are the same.
slope of BD: m=rise/run=4/-2=-2 (the run is negative because to get to B from D on the grid, you have to move from right to left, then upward. If the horizontal move is from left to right, the run is positive)
slope of EG: m=rise/run=2/-1=-2
EG and BD have the same slope, so they are parallel.
Answer:
b. DAC≅DBC
Step-by-step explanation:
∠DCB≅∠DCA=90° as they are right angles at the perpendicular lines
DC=DC reflexive property(they are the same line)
AC=CB they are both the radius of the same circle
DAC≅DBC due to SAS(Side angle Side)
5 · 5 - 4 · 4 = 9 sorry if I'm wrong
the dots mean to multiply
