Let the area of a PQR with vertices P(5,4), Q(-2,4) and R(a,b) be 35 square units. If its orthocenter and centroid are O (2, 145 ) and C(c,d) respectively, then c+2d is equal to
- 3
- 73
- 2
- 83
Answer
(1) 3
Solution
PQ is horizontal with PQ=7: 12 7 |b-4|=35 |b-4|=10
Altitude from R is vertical and passes through O (2, 145 ) a=2
[figure]
PO QR: slope PO= 25 slope QR=- 52= b-44 b=-6, so R(2,-6)
Centroid C= ( 5-2+23, 4+4-63 )= ( 53, 23 ) c+2d=3
Answer: (1)