Question
Two ships are on opposite sides in front of a lighthouse
in such a way that all three of them are in line. The angles of depression of two ships from the top of a lighthouse are 30° and 60°. If the distance between the ships is 230√3  m, then find the height (in m) of the lighthouse.Solution
Let the length of the lighthouse = BD m Use this property - When the angles of a triangle are 30 ° ,60 ° , and 90° respectively, the ratio of the opposite sides is 1: √ 3:2. When Triangle BDC – The opposite side of angle 30° = 1 Similarly - angle 60° =     √ 3, and angle 90° =2 Triangle ABD -opposite side of angle 30 ° =BD = 1= √ 3……. means √ 3times. so -opposite side of angle60° =AD = √ 3 = √ 3× √ 3 =3 now – AD + DC = AC 4= 230 √ 3 1= (230 √ 3)/4 Now height = BD = √ 3= (230 √ 3/4) × √ 3= (230 ×3)/4 =690/4 =172.5meter
32 X 25 ÷ 4 + 12 of 30 = ? X 5 - 30Â
Evaluate: 18 ÷ 3 × 4 + 6 − 5
25% of 250 + 32% of 200 = ? ÷ √ 16
15% of 1800 + 22 = ?Â
118 × 6 + 13 + 83 = ?
- What will come in the place of question mark (?) in the given expression?
35% of 400 - 20% of 300 = (? - 30) X 2 - What will come in place of the question mark (?) in the following questions?
120÷(5×2)+8=? √? = 32% of 900 + 48% of 50
 Â
