Question

Q1. Find y, if √12 - √147 + y√3 = 0

Q2. Without using tables or calculators, find the value of Sin45° - Cos30°

Hints: Sin45° = √2/2 Cos 30° = √3/2.

Answer 1

Q1. y = 5 Q2. (√2 - √3)/2

Explanation:

Q1

√12 - √147 + y√3 = 0

Taking -√147 and √12 to the right hand side, we have

y√3 = √147 - √12

y√3 = √(3 × 49) - √(3 × 4)

y√3 = √3 × √49 - √3 × √4

y√3 = √3 × 7 - √3 × 2

y√3 = 7√3 - 2√3

y√3 = 5√3

Dividing both sides by √3, we have

y√3/√3 = 5√3/√3

y = 5

Q2

Sin45° - Cos30°

Since Sin45° = √2/2 and Cos 30° = √3/2

Substituting these values into the equation, we have

Sin45° - Cos30° = √2/2 - √3/2

Taking L.C.M of both factors, we have

Sin45° - Cos30° = (√2 - √3)/2