My teacher hasn't taught the topic yet, but thinks we can do this without any guidance. Can you please help.

melvsky May 6, 2018

#1**+2 **

Both questions begin by making use of the Pythagoras theorem.

For the first one, start by saying that 9^2 + r^2 = (6 + r)^2, tidy up and solve for r.

The second one is asking you if the triangle is rightangled (Pythagoras again), if it is then ST will be a tangent.

Guest May 6, 2018

#2**+2 **

Q1:

(6+r)^{2} = 9^{2} + r^{2}

6^{2} + 2*6*r+r^{2} = 9^{2} + r^{2}

6^{2} + 2*6*r = 9^{2}

2*6*r = 9^{2 }- 6^{2}

r = ( 9^{2 }- 6^{2 }) / ( 2*6 )

Q2:

by using pythagoras rule

if RT^{2} = RS^{2 }+ ST^{2 }is true , ST is tangent to the circle.

(5+8)^{2} = 5^{2 }+ 12^{2}

(13)^{2} = 5^{2 }+ 12^{2}

169 = 25^{ }+ 144

169 = 169

yas

Guest May 6, 2018

edited by
Guest
May 6, 2018