Question
The comer points A, B, C and D of a ranch are such that B is 8km directly East of A and C is 6km from B on a bearing of 30°. D is 7km from C on a bearing of 300°.
(a) Using a scale of 1cm to represent 1km, draw a diagram to show the positions of A, B, C and D.
(b) Use the scale drawing to determine:
(i) The bearing of A from D;
(ii) The distance BD in kilometers.
(a) Using a scale of 1cm to represent 1km, draw a diagram to show the positions of A, B, C and D.
(b) Use the scale drawing to determine:
(i) The bearing of A from D;
(ii) The distance BD in kilometers.
Answers
oobleck
This looks suspiciously like the PQRS ranch.
Where do you get stuck? Remember the law of cosines and the law of sines.
Where do you get stuck? Remember the law of cosines and the law of sines.
henry2,
AD = AB+BC+CD.
DA = -AD.
All angles are measured CW from +y-axis.
(I). AD = 8km[90o] + 6km[30o] + 7km[300o].
AD = (8*sin90+6*sin30+7*sin300) + (8*Cos90+6*Cos30+7*Cos300)I,
AD = 4.94 + 8.7i = 10km[30o].
DA = -AD = 10[30+180] = 10km[210o].
(ii). BD = BC + CD.
BD = 6km[30o] + 7km]300o].
BD = ?
DA = -AD.
All angles are measured CW from +y-axis.
(I). AD = 8km[90o] + 6km[30o] + 7km[300o].
AD = (8*sin90+6*sin30+7*sin300) + (8*Cos90+6*Cos30+7*Cos300)I,
AD = 4.94 + 8.7i = 10km[30o].
DA = -AD = 10[30+180] = 10km[210o].
(ii). BD = BC + CD.
BD = 6km[30o] + 7km]300o].
BD = ?