Question

in a triangle abc ;right angled at b ,bc =7 cm and ac - ab = 1 cm find the value of cosA-sin A hurry​

Answer 1

$cosA-sinA=17/25=.68$

Step-by-step explanation:

Given,ABC is a triangle  right angle at B

$bc=7cm$         $ac-ab=1cm$

$ac=ab+1$

$\left ( ac \right )^{2}=\left ( ab \right )^{2}+\left ( bc \right )^{2}$

$\left ( ab+1 \right )^{2}=\left ( ab \right )^{2}+\left ( bc \right )^{2}$

$\left ( ab \right )^{2}+2ab+1=\left ( ab \right )^{2}+\left ( 7 \right )^{2}$

$2ab=49-1$

$ab=48/2$

$ab=24cm$

$ac=ab+1$

$ab=24+1=25cm$

$cosA-sinA=ab/ac-bc/ac$

$=24/25-7/25$

$cosA-sinA=17/25=.68$

Answer 2

Answer:

Step-by-step explanation:

Given,ABC is a triangle right angle at B

bc=7cm ac-ab=1cm

ac=ab+1

\left ( ac \right )^{2}=\left ( ab \right )^{2}+\left ( bc \right )^{2}

\left ( ab+1 \right )^{2}=\left ( ab \right )^{2}+\left ( bc \right )^{2}

\left ( ab \right )^{2}+2ab+1=\left ( ab \right )^{2}+\left ( 7 \right )^{2}

2ab=49-1

ab=48/2

ab=24cm

ac=ab+1

ab=24+1=25cm

cosA-sinA=ab/ac-bc/ac

=24/25-7/25

cosA-sinA=17/25=.68