Question

Evaluate the following :
(i) sin 60° cos 30° + sin 30° cos 60° (ii) 2 tan2 45° + cos2 30° – sin2 60°

NCERT Class X
Mathematics - Mathematics

Chapter _INTRODUCTION TO
TRIGONOMETRY

Answer 1

(i) sin 60° cos 30° + sin 30° cos 60°
= Root 3/ 2*1/2 + 1/2*Root 3/ 2
= Root 3/4 + Root 3/4
= Root 3/2

(ii) 2 tan2 45° + cos2 30° – sin2 60°
= 2*1*1 + (Root 3/ 2)*(Root 3/ 2) - (Root 3/ 2)*(Root 3/ 2)
= 2

Answer 2

Answer:

1. √3/2

2 2

Step-by-step explanation:

sin 60° cos 30° + sin 30° cos 60°

= √ 3/ 2*1/2 + 1/2* √3/2 = √3/4 + √3/4

= √3/2

(ii) 2 tan2 45° + cos2 30° – sin2 60° = 2*1*1 + (√3/ 2)*(√3/ 2) - (√3/ 2)*(√ 3/2) = 2