wiz-icon
MyQuestionIcon
MyQuestionIcon
2
You visited us 2 times! Enjoying our articles? Unlock Full Access!
Question

In a ABC, if sin3A=0, then it is

A
equilateral
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
B
right angled
No worries! We‘ve got your back. Try BYJU‘S free classes today!
C
isosceles
No worries! We‘ve got your back. Try BYJU‘S free classes today!
D
has at least one angle 600
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
Open in App
Solution

The correct options are
A equilateral
D has at least one angle 600
sin3A=0
sin3A+sin3B+sin3C=0 by expanding the summation
2sin(32(A+B))cos(32(AB))+sin3C=0 using compound angle formula.
2sin(32(A+B))cos(32(AB))+2sin3C2cos3C2=0 using multiple angle formula.
2sin(3π23C2)cos(32(AB))+2sin3C2cos3C2=0 since A+B+C=π
2cos3C2cos(32(AB))+2sin3C2cos3C2=0
cos3C2[cos(32(AB))cos3C2]=0 by taking common terms
cos3C2[cos(32(AB))+cos(32(A+B))]=0 since cos(πθ)=cosθ
cos3C2cos3A2cos3B2=0 by compound angle formula
cos3C2=cos900
3C2=900
C=600
C=600 or A=600 or B=600

flag
Suggest Corrections
thumbs-up
0
Join BYJU'S Learning Program
similar_icon
Related Videos
thumbnail
lock
MATHEMATICS
Watch in App
Join BYJU'S Learning Program
CrossIcon