Question

Triangle abc angle b is equal to 90 degrees ab is equal to 12 cm and BC is equal to 5 cm find the value of cos c

Answer 1

Answer:

From figure: △ABCis a right angled triangle

AC

2

=BC

2

+AB

2

AC

2

=(5)

2

+(12)

2

AC

2

=25+144

AC

2

=169=(13)

2

or AC=13

Now from figure,

i.cosA=

AC

AB

=

13

12

ii.cscA=

BC

AC

=

5

13

iii.cosC=

AC

BC

=

13

5

iv.cscC=

AB

AC

=

12

13

Hence, proved.